Switch back to custom geometry types, unified with layout primitives 🏞

45 files changed, 1656 insertions, 1342 deletions

diff --git a/Cargo.toml b/Cargo.toml
index a9d8011d..96385771 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -24,7 +24,6 @@ lto = true
 [dependencies]
 async-trait = "0.1"
 fontdock = { path = "../fontdock", default-features = false }
-kurbo = "0.6.3"
 tide = { path = "../tide" }
 ttf-parser = "0.8.2"
 unicode-xid = "0.2"
@@ -33,6 +32,7 @@ serde = { version = "1", features = ["derive"], optional = true }
 [dev-dependencies]
 criterion = "0.3"
 futures-executor = "0.3"
+kurbo = "0.6.3"
 serde_json = "1"
 raqote = { version = "0.8", default-features = false }
 
diff --git a/src/eval/convert.rs b/src/eval/convert.rs
index 4c177c5b..69ef2506 100644
--- a/src/eval/convert.rs
+++ b/src/eval/convert.rs
@@ -6,8 +6,7 @@ use fontdock::{FontStretch, FontStyle, FontWeight};
 
 use super::{Value, ValueDict, ValueFunc};
 use crate::diag::Diag;
-use crate::geom::Linear;
-use crate::layout::{Dir, SpecAlign};
+use crate::geom::{Dir, Length, Linear, Relative};
 use crate::paper::Paper;
 use crate::syntax::{Ident, SpanWith, Spanned, SynTree};
 
@@ -37,26 +36,53 @@ impl<T: Convert> Convert for Spanned<T> {
     }
 }
 
-/// A value type that matches [length] values.
-///
-/// [length]: enum.Value.html#variant.Length
-pub struct Absolute(pub f64);
-
-impl From<Absolute> for f64 {
-    fn from(abs: Absolute) -> f64 {
-        abs.0
-    }
+macro_rules! convert_match {
+    ($type:ty, $name:expr, $($p:pat => $r:expr),* $(,)?) => {
+        impl $crate::eval::Convert for $type {
+            fn convert(
+                value: $crate::syntax::Spanned<$crate::eval::Value>
+            ) -> (Result<Self, $crate::eval::Value>, Option<$crate::diag::Diag>) {
+                #[allow(unreachable_patterns)]
+                match value.v {
+                    $($p => (Ok($r), None)),*,
+                    v => {
+                        let err = $crate::error!("expected {}, found {}", $name, v.ty());
+                        (Err(v), Some(err))
+                    },
+                }
+            }
+        }
+    };
 }
 
-/// A value type that matches [relative] values.
-///
-/// [relative]: enum.Value.html#variant.Relative
-pub struct Relative(pub f64);
-
-impl From<Relative> for f64 {
-    fn from(rel: Relative) -> f64 {
-        rel.0
-    }
+macro_rules! convert_ident {
+    ($type:ty, $name:expr, $parse:expr) => {
+        impl $crate::eval::Convert for $type {
+            fn convert(
+                value: $crate::syntax::Spanned<$crate::eval::Value>,
+            ) -> (
+                Result<Self, $crate::eval::Value>,
+                Option<$crate::diag::Diag>,
+            ) {
+                match value.v {
+                    Value::Ident(id) => {
+                        if let Some(thing) = $parse(&id) {
+                            (Ok(thing), None)
+                        } else {
+                            (
+                                Err($crate::eval::Value::Ident(id)),
+                                Some($crate::error!("invalid {}", $name)),
+                            )
+                        }
+                    }
+                    v => {
+                        let err = $crate::error!("expected {}, found {}", $name, v.ty());
+                        (Err(v), Some(err))
+                    }
+                }
+            }
+        }
+    };
 }
 
 /// A value type that matches [identifier] and [string] values.
@@ -79,70 +105,31 @@ impl Deref for StringLike {
     }
 }
 
-macro_rules! impl_match {
-    ($type:ty, $name:expr, $($p:pat => $r:expr),* $(,)?) => {
-        impl Convert for $type {
-            fn convert(value: Spanned<Value>) -> (Result<Self, Value>, Option<Diag>) {
-                #[allow(unreachable_patterns)]
-                match value.v {
-                    $($p => (Ok($r), None)),*,
-                    v => {
-                        let err = error!("expected {}, found {}", $name, v.ty());
-                        (Err(v), Some(err))
-                    },
-                }
-            }
-        }
-    };
-}
-
-impl_match!(Value, "value", v => v);
-impl_match!(Ident, "identifier", Value::Ident(v) => v);
-impl_match!(bool, "bool", Value::Bool(v) => v);
-impl_match!(i64, "integer", Value::Int(v) => v);
-impl_match!(f64, "float",
+convert_match!(Value, "value", v => v);
+convert_match!(Ident, "identifier", Value::Ident(v) => v);
+convert_match!(bool, "bool", Value::Bool(v) => v);
+convert_match!(i64, "integer", Value::Int(v) => v);
+convert_match!(f64, "float",
     Value::Int(v) => v as f64,
     Value::Float(v) => v,
 );
-impl_match!(Absolute, "length", Value::Length(v) => Absolute(v));
-impl_match!(Relative, "relative", Value::Relative(v) => Relative(v));
-impl_match!(Linear, "linear",
+convert_match!(Length, "length", Value::Length(v) => v);
+convert_match!(Relative, "relative", Value::Relative(v) => v);
+convert_match!(Linear, "linear",
     Value::Linear(v) => v,
-    Value::Length(v) => Linear::abs(v),
-    Value::Relative(v) => Linear::rel(v),
+    Value::Length(v) => v.into(),
+    Value::Relative(v) => v.into(),
 );
-impl_match!(String, "string", Value::Str(v) => v);
-impl_match!(SynTree, "tree", Value::Content(v) => v);
-impl_match!(ValueDict, "dictionary", Value::Dict(v) => v);
-impl_match!(ValueFunc, "function", Value::Func(v) => v);
-impl_match!(StringLike, "identifier or string",
+convert_match!(String, "string", Value::Str(v) => v);
+convert_match!(SynTree, "tree", Value::Content(v) => v);
+convert_match!(ValueDict, "dictionary", Value::Dict(v) => v);
+convert_match!(ValueFunc, "function", Value::Func(v) => v);
+convert_match!(StringLike, "identifier or string",
     Value::Ident(Ident(v)) => StringLike(v),
     Value::Str(v) => StringLike(v),
 );
 
-macro_rules! impl_ident {
-    ($type:ty, $name:expr, $parse:expr) => {
-        impl Convert for $type {
-            fn convert(value: Spanned<Value>) -> (Result<Self, Value>, Option<Diag>) {
-                match value.v {
-                    Value::Ident(id) => {
-                        if let Some(thing) = $parse(&id) {
-                            (Ok(thing), None)
-                        } else {
-                            (Err(Value::Ident(id)), Some(error!("invalid {}", $name)))
-                        }
-                    }
-                    v => {
-                        let err = error!("expected {}, found {}", $name, v.ty());
-                        (Err(v), Some(err))
-                    }
-                }
-            }
-        }
-    };
-}
-
-impl_ident!(Dir, "direction", |v| match v {
+convert_ident!(Dir, "direction", |v| match v {
     "ltr" => Some(Self::LTR),
     "rtl" => Some(Self::RTL),
     "ttb" => Some(Self::TTB),
@@ -150,18 +137,9 @@ impl_ident!(Dir, "direction", |v| match v {
     _ => None,
 });
 
-impl_ident!(SpecAlign, "alignment", |v| match v {
-    "left" => Some(Self::Left),
-    "right" => Some(Self::Right),
-    "top" => Some(Self::Top),
-    "bottom" => Some(Self::Bottom),
-    "center" => Some(Self::Center),
-    _ => None,
-});
-
-impl_ident!(FontStyle, "font style", Self::from_str);
-impl_ident!(FontStretch, "font stretch", Self::from_str);
-impl_ident!(Paper, "paper", Self::from_name);
+convert_ident!(FontStyle, "font style", Self::from_str);
+convert_ident!(FontStretch, "font stretch", Self::from_str);
+convert_ident!(Paper, "paper", Self::from_name);
 
 impl Convert for FontWeight {
     fn convert(value: Spanned<Value>) -> (Result<Self, Value>, Option<Diag>) {
diff --git a/src/eval/mod.rs b/src/eval/mod.rs
index 2c6f4d7c..fc8bbbd6 100644
--- a/src/eval/mod.rs
+++ b/src/eval/mod.rs
@@ -1,7 +1,8 @@
 //! Evaluation of syntax trees.
 
-mod args;
+#[macro_use]
 mod convert;
+mod args;
 mod dict;
 mod scope;
 mod state;
@@ -22,10 +23,10 @@ use fontdock::FontStyle;
 
 use crate::diag::Diag;
 use crate::diag::{Deco, Feedback, Pass};
-use crate::layout::nodes::{
+use crate::geom::{Gen, Length, Relative, Spec, Switch};
+use crate::layout::{
     Document, LayoutNode, Pad, Pages, Par, Softness, Spacing, Stack, Text,
 };
-use crate::layout::{Gen2, Spec2, Switch};
 use crate::syntax::*;
 
 /// Evaluate a syntax tree into a document.
@@ -168,7 +169,7 @@ impl EvalContext {
                         dirs,
                         children,
                         aligns,
-                        expand: Spec2::new(true, true),
+                        expand: Spec::new(true, true),
                     }),
                 }),
             })
@@ -195,7 +196,7 @@ impl EvalContext {
                 line_spacing,
                 children,
                 aligns,
-                expand: Gen2::new(false, expand_cross).switch(dirs),
+                expand: Gen::new(false, expand_cross).switch(dirs),
             });
         }
     }
@@ -337,7 +338,7 @@ impl Eval for NodeRaw {
             dirs: ctx.state.dirs,
             children,
             aligns: ctx.state.aligns,
-            expand: Spec2::new(false, false),
+            expand: Spec::new(false, false),
         });
 
         ctx.state.text.fallback = prev;
@@ -366,8 +367,8 @@ impl Eval for Lit {
             Lit::Bool(v) => Value::Bool(v),
             Lit::Int(v) => Value::Int(v),
             Lit::Float(v) => Value::Float(v),
-            Lit::Length(v) => Value::Length(v.as_raw()),
-            Lit::Percent(v) => Value::Relative(v / 100.0),
+            Lit::Length(v, unit) => Value::Length(Length::with_unit(v, unit)),
+            Lit::Percent(v) => Value::Relative(Relative::new(v / 100.0)),
             Lit::Color(v) => Value::Color(v),
             Lit::Str(ref v) => Value::Str(v.clone()),
             Lit::Dict(ref v) => Value::Dict(v.eval(ctx)),
@@ -473,7 +474,6 @@ fn neg(ctx: &mut EvalContext, span: Span, value: Value) -> Value {
 
 /// Compute the sum of two values.
 fn add(ctx: &mut EvalContext, span: Span, lhs: Value, rhs: Value) -> Value {
-    use crate::geom::Linear as Lin;
     use Value::*;
     match (lhs, rhs) {
         // Numbers to themselves.
@@ -484,15 +484,15 @@ fn add(ctx: &mut EvalContext, span: Span, lhs: Value, rhs: Value) -> Value {
 
         // Lengths, relatives and linears to themselves.
         (Length(a), Length(b)) => Length(a + b),
-        (Length(a), Relative(b)) => Linear(Lin::abs(a) + Lin::rel(b)),
-        (Length(a), Linear(b)) => Linear(Lin::abs(a) + b),
+        (Length(a), Relative(b)) => Linear(a + b),
+        (Length(a), Linear(b)) => Linear(a + b),
 
-        (Relative(a), Length(b)) => Linear(Lin::rel(a) + Lin::abs(b)),
+        (Relative(a), Length(b)) => Linear(a + b),
         (Relative(a), Relative(b)) => Relative(a + b),
-        (Relative(a), Linear(b)) => Linear(Lin::rel(a) + b),
+        (Relative(a), Linear(b)) => Linear(a + b),
 
-        (Linear(a), Length(b)) => Linear(a + Lin::abs(b)),
-        (Linear(a), Relative(b)) => Linear(a + Lin::rel(b)),
+        (Linear(a), Length(b)) => Linear(a + b),
+        (Linear(a), Relative(b)) => Linear(a + b),
         (Linear(a), Linear(b)) => Linear(a + b),
 
         // Complex data types to themselves.
@@ -509,7 +509,6 @@ fn add(ctx: &mut EvalContext, span: Span, lhs: Value, rhs: Value) -> Value {
 
 /// Compute the difference of two values.
 fn sub(ctx: &mut EvalContext, span: Span, lhs: Value, rhs: Value) -> Value {
-    use crate::geom::Linear as Lin;
     use Value::*;
     match (lhs, rhs) {
         // Numbers from themselves.
@@ -520,13 +519,13 @@ fn sub(ctx: &mut EvalContext, span: Span, lhs: Value, rhs: Value) -> Value {
 
         // Lengths, relatives and linears from themselves.
         (Length(a), Length(b)) => Length(a - b),
-        (Length(a), Relative(b)) => Linear(Lin::abs(a) - Lin::rel(b)),
-        (Length(a), Linear(b)) => Linear(Lin::abs(a) - b),
-        (Relative(a), Length(b)) => Linear(Lin::rel(a) - Lin::abs(b)),
+        (Length(a), Relative(b)) => Linear(a - b),
+        (Length(a), Linear(b)) => Linear(a - b),
+        (Relative(a), Length(b)) => Linear(a - b),
         (Relative(a), Relative(b)) => Relative(a - b),
-        (Relative(a), Linear(b)) => Linear(Lin::rel(a) - b),
-        (Linear(a), Length(b)) => Linear(a - Lin::abs(b)),
-        (Linear(a), Relative(b)) => Linear(a - Lin::rel(b)),
+        (Relative(a), Linear(b)) => Linear(a - b),
+        (Linear(a), Length(b)) => Linear(a - b),
+        (Linear(a), Relative(b)) => Linear(a - b),
         (Linear(a), Linear(b)) => Linear(a - b),
 
         (a, b) => {
@@ -561,8 +560,8 @@ fn mul(ctx: &mut EvalContext, span: Span, lhs: Value, rhs: Value) -> Value {
         (Float(a), Linear(b)) => Linear(a * b),
 
         // Integers with strings.
-        (Int(a), Str(b)) => Str(b.repeat(a.max(0) as usize)),
-        (Str(a), Int(b)) => Str(a.repeat(b.max(0) as usize)),
+        (Int(a), Str(b)) => Str(b.repeat(0.max(a) as usize)),
+        (Str(a), Int(b)) => Str(a.repeat(0.max(b) as usize)),
 
         (a, b) => {
             ctx.diag(error!(span, "cannot multiply {} with {}", a.ty(), b.ty()));
diff --git a/src/eval/state.rs b/src/eval/state.rs
index 7372b851..3ae6b414 100644
--- a/src/eval/state.rs
+++ b/src/eval/state.rs
@@ -5,9 +5,7 @@ use std::rc::Rc;
 use fontdock::{fallback, FallbackTree, FontStretch, FontStyle, FontVariant, FontWeight};
 
 use super::Scope;
-use crate::geom::{Linear, Size};
-use crate::layout::{Dir, Gen2, GenAlign, Sides};
-use crate::length::Length;
+use crate::geom::{Align, Dir, Gen, Length, Linear, Relative, Sides, Size};
 use crate::paper::{Paper, PaperClass, PAPER_A4};
 
 /// The active evaluation state.
@@ -20,9 +18,9 @@ pub struct State {
     /// The page state.
     pub page: PageState,
     /// The active layouting directions.
-    pub dirs: Gen2<Dir>,
+    pub dirs: Gen<Dir>,
     /// The active alignments.
-    pub aligns: Gen2<GenAlign>,
+    pub aligns: Gen<Align>,
 }
 
 impl Default for State {
@@ -31,8 +29,8 @@ impl Default for State {
             scope: crate::library::_std(),
             text: TextState::default(),
             page: PageState::default(),
-            dirs: Gen2::new(Dir::TTB, Dir::LTR),
-            aligns: Gen2::new(GenAlign::Start, GenAlign::Start),
+            dirs: Gen::new(Dir::TTB, Dir::LTR),
+            aligns: Gen::new(Align::Start, Align::Start),
         }
     }
 }
@@ -62,22 +60,22 @@ pub struct TextState {
 
 impl TextState {
     /// The absolute font size.
-    pub fn font_size(&self) -> f64 {
+    pub fn font_size(&self) -> Length {
         self.font_size.eval()
     }
 
     /// The absolute word spacing.
-    pub fn word_spacing(&self) -> f64 {
+    pub fn word_spacing(&self) -> Length {
         self.word_spacing.eval(self.font_size())
     }
 
     /// The absolute line spacing.
-    pub fn line_spacing(&self) -> f64 {
+    pub fn line_spacing(&self) -> Length {
         self.line_spacing.eval(self.font_size())
     }
 
     /// The absolute paragraph spacing.
-    pub fn par_spacing(&self) -> f64 {
+    pub fn par_spacing(&self) -> Length {
         self.par_spacing.eval(self.font_size())
     }
 }
@@ -105,10 +103,10 @@ impl Default for TextState {
             },
             strong: false,
             emph: false,
-            font_size: FontSize::abs(Length::pt(11.0).as_raw()),
-            word_spacing: Linear::rel(0.25),
-            line_spacing: Linear::rel(0.2),
-            par_spacing: Linear::rel(0.5),
+            font_size: FontSize::abs(Length::pt(11.0)),
+            word_spacing: Relative::new(0.25).into(),
+            line_spacing: Relative::new(0.2).into(),
+            par_spacing: Relative::new(0.5).into(),
         }
     }
 }
@@ -117,7 +115,7 @@ impl Default for TextState {
 #[derive(Debug, Clone, PartialEq)]
 pub struct FontSize {
     /// The base font size, updated whenever the font size is set absolutely.
-    pub base: f64,
+    pub base: Length,
     /// The scale to apply on the base font size, updated when the font size
     /// is set relatively.
     pub scale: Linear,
@@ -125,17 +123,17 @@ pub struct FontSize {
 
 impl FontSize {
     /// Create a new font size.
-    pub fn new(base: f64, scale: Linear) -> Self {
-        Self { base, scale }
+    pub fn new(base: Length, scale: impl Into<Linear>) -> Self {
+        Self { base, scale: scale.into() }
     }
 
     /// Create a new font size with the given `base` and a scale of `1.0`.
-    pub fn abs(base: f64) -> Self {
-        Self::new(base, Linear::rel(1.0))
+    pub fn abs(base: Length) -> Self {
+        Self::new(base, Relative::ONE)
     }
 
     /// Compute the absolute font size.
-    pub fn eval(&self) -> f64 {
+    pub fn eval(&self) -> Length {
         self.scale.eval(self.base)
     }
 }
diff --git a/src/eval/value.rs b/src/eval/value.rs
index c4b11ebe..56dadfc3 100644
--- a/src/eval/value.rs
+++ b/src/eval/value.rs
@@ -6,7 +6,7 @@ use std::rc::Rc;
 
 use super::{Args, Dict, Eval, EvalContext, SpannedEntry};
 use crate::color::RgbaColor;
-use crate::geom::Linear;
+use crate::geom::{Length, Linear, Relative};
 use crate::syntax::{Ident, SynTree};
 
 /// A computational value.
@@ -23,14 +23,9 @@ pub enum Value {
     /// A floating-point number: `1.2, 200%`.
     Float(f64),
     /// A length: `2cm, 5.2in`.
-    Length(f64),
+    Length(Length),
     /// A relative value: `50%`.
-    ///
-    /// _Note_: `50%` is represented as `0.5` here, but as `50.0` in the
-    /// corresponding [literal].
-    ///
-    /// [literal]: ../syntax/ast/enum.Lit.html#variant.Percent
-    Relative(f64),
+    Relative(Relative),
     /// A combination of an absolute length and a relative value: `20% + 5cm`.
     Linear(Linear),
     /// A color value with alpha channel: `#f79143ff`.
diff --git a/src/export/pdf.rs b/src/export/pdf.rs
index 02b54471..722728ff 100644
--- a/src/export/pdf.rs
+++ b/src/export/pdf.rs
@@ -14,8 +14,8 @@ use tide::{PdfWriter, Rect, Ref, Trailer, Version};
 use ttf_parser::{name_id, GlyphId};
 
 use crate::font::FontLoader;
+use crate::geom::Length;
 use crate::layout::{BoxLayout, LayoutElement};
-use crate::length::Length;
 
 /// Export a list of layouts into a _PDF_ document.
 ///
@@ -110,8 +110,8 @@ impl<'a, W: Write> PdfExporter<'a, W> {
             let rect = Rect::new(
                 0.0,
                 0.0,
-                Length::raw(page.size.width).as_pt() as f32,
-                Length::raw(page.size.height).as_pt() as f32,
+                page.size.width.to_pt() as f32,
+                page.size.height.to_pt() as f32,
             );
 
             self.writer.write_obj(
@@ -136,7 +136,7 @@ impl<'a, W: Write> PdfExporter<'a, W> {
         // Font switching actions are only written when the face used for
         // shaped text changes. Hence, we need to remember the active face.
         let mut face = FaceId::MAX;
-        let mut size = 0.0;
+        let mut size = Length::ZERO;
 
         for (pos, element) in &page.elements {
             match element {
@@ -147,12 +147,12 @@ impl<'a, W: Write> PdfExporter<'a, W> {
                         size = shaped.size;
                         text.tf(
                             self.to_pdf[&shaped.face] as u32 + 1,
-                            Length::raw(size).as_pt() as f32,
+                            size.to_pt() as f32,
                         );
                     }
 
-                    let x = Length::raw(pos.x).as_pt();
-                    let y = Length::raw(page.size.height - pos.y - size).as_pt();
+                    let x = pos.x.to_pt();
+                    let y = (page.size.height - pos.y - size).to_pt();
                     text.tm(1.0, 0.0, 0.0, 1.0, x as f32, y as f32);
                     text.tj(shaped.encode_glyphs_be());
                 }
diff --git a/src/geom.rs b/src/geom.rs
deleted file mode 100644
index 90c7ac62..00000000
--- a/src/geom.rs
+++ /dev/null
@@ -1,235 +0,0 @@
-//! Geometrical types.
-
-#[doc(no_inline)]
-pub use kurbo::*;
-
-use std::fmt::{self, Debug, Formatter};
-use std::ops::*;
-
-use crate::layout::{Dir, Gen2, GenAlign, Get, Side, Spec2, SpecAxis, Switch};
-
-macro_rules! impl_2d {
-    ($t:ty, $x:ident, $y:ident) => {
-        impl Get<SpecAxis> for $t {
-            type Component = f64;
-
-            fn get(self, axis: SpecAxis) -> f64 {
-                match axis {
-                    SpecAxis::Horizontal => self.$x,
-                    SpecAxis::Vertical => self.$y,
-                }
-            }
-
-            fn get_mut(&mut self, axis: SpecAxis) -> &mut f64 {
-                match axis {
-                    SpecAxis::Horizontal => &mut self.$x,
-                    SpecAxis::Vertical => &mut self.$y,
-                }
-            }
-        }
-
-        impl Switch for $t {
-            type Other = Gen2<f64>;
-
-            fn switch(self, dirs: Gen2<Dir>) -> Self::Other {
-                Spec2::new(self.$x, self.$y).switch(dirs)
-            }
-        }
-    };
-}
-
-impl_2d!(Point, x, y);
-impl_2d!(Vec2, x, y);
-impl_2d!(Size, width, height);
-
-impl Get<Side> for Rect {
-    type Component = f64;
-
-    fn get(self, side: Side) -> f64 {
-        match side {
-            Side::Left => self.x0,
-            Side::Top => self.y0,
-            Side::Right => self.x1,
-            Side::Bottom => self.y1,
-        }
-    }
-
-    fn get_mut(&mut self, side: Side) -> &mut f64 {
-        match side {
-            Side::Left => &mut self.x0,
-            Side::Top => &mut self.y0,
-            Side::Right => &mut self.x1,
-            Side::Bottom => &mut self.y1,
-        }
-    }
-}
-
-/// Additional methods for [sizes].
-///
-/// [sizes]: ../../kurbo/struct.Size.html
-pub trait SizeExt {
-    /// Whether the given size fits into this one, that is, both coordinate
-    /// values are smaller or equal.
-    fn fits(self, other: Self) -> bool;
-
-    /// The anchor position for an object to be aligned in a container with this
-    /// size and the given directions.
-    fn anchor(self, dirs: Gen2<Dir>, aligns: Gen2<GenAlign>) -> Point;
-}
-
-impl SizeExt for Size {
-    fn fits(self, other: Self) -> bool {
-        self.width >= other.width && self.height >= other.height
-    }
-
-    fn anchor(self, dirs: Gen2<Dir>, aligns: Gen2<GenAlign>) -> Point {
-        fn anchor(length: f64, dir: Dir, align: GenAlign) -> f64 {
-            match if dir.is_positive() { align } else { align.inv() } {
-                GenAlign::Start => 0.0,
-                GenAlign::Center => length / 2.0,
-                GenAlign::End => length,
-            }
-        }
-
-        let switched = self.switch(dirs);
-        let generic = Gen2::new(
-            anchor(switched.main, dirs.main, aligns.main),
-            anchor(switched.cross, dirs.cross, aligns.cross),
-        );
-
-        generic.switch(dirs).to_point()
-    }
-}
-
-/// A function that depends linearly on one value.
-///
-/// This represents a function `f(x) = rel * x + abs`.
-#[derive(Copy, Clone, PartialEq)]
-pub struct Linear {
-    /// The relative part.
-    pub rel: f64,
-    /// The absolute part.
-    pub abs: f64,
-}
-
-impl Linear {
-    /// The constant zero function.
-    pub const ZERO: Linear = Linear { rel: 0.0, abs: 0.0 };
-
-    /// Create a new linear function.
-    pub fn new(rel: f64, abs: f64) -> Self {
-        Self { rel, abs }
-    }
-
-    /// Create a new linear function with only a relative component.
-    pub fn rel(rel: f64) -> Self {
-        Self { rel, abs: 0.0 }
-    }
-
-    /// Create a new linear function with only an absolute component.
-    pub fn abs(abs: f64) -> Self {
-        Self { rel: 0.0, abs }
-    }
-
-    /// Evaluate the linear function with the given value.
-    pub fn eval(self, x: f64) -> f64 {
-        self.rel * x + self.abs
-    }
-}
-
-impl Add for Linear {
-    type Output = Self;
-
-    fn add(self, other: Self) -> Self {
-        Self {
-            rel: self.rel + other.rel,
-            abs: self.abs + other.abs,
-        }
-    }
-}
-
-impl AddAssign for Linear {
-    fn add_assign(&mut self, other: Self) {
-        self.rel += other.rel;
-        self.abs += other.abs;
-    }
-}
-
-impl Sub for Linear {
-    type Output = Self;
-
-    fn sub(self, other: Self) -> Self {
-        Self {
-            rel: self.rel - other.rel,
-            abs: self.abs - other.abs,
-        }
-    }
-}
-
-impl SubAssign for Linear {
-    fn sub_assign(&mut self, other: Self) {
-        self.rel -= other.rel;
-        self.abs -= other.abs;
-    }
-}
-
-impl Mul<f64> for Linear {
-    type Output = Self;
-
-    fn mul(self, other: f64) -> Self {
-        Self {
-            rel: self.rel * other,
-            abs: self.abs * other,
-        }
-    }
-}
-
-impl MulAssign<f64> for Linear {
-    fn mul_assign(&mut self, other: f64) {
-        self.rel *= other;
-        self.abs *= other;
-    }
-}
-
-impl Mul<Linear> for f64 {
-    type Output = Linear;
-
-    fn mul(self, other: Linear) -> Linear {
-        Linear {
-            rel: self * other.rel,
-            abs: self * other.abs,
-        }
-    }
-}
-
-impl Div<f64> for Linear {
-    type Output = Self;
-
-    fn div(self, other: f64) -> Self {
-        Self {
-            rel: self.rel / other,
-            abs: self.abs / other,
-        }
-    }
-}
-
-impl DivAssign<f64> for Linear {
-    fn div_assign(&mut self, other: f64) {
-        self.rel /= other;
-        self.abs /= other;
-    }
-}
-
-impl Neg for Linear {
-    type Output = Self;
-
-    fn neg(self) -> Self {
-        Self { rel: -self.rel, abs: -self.abs }
-    }
-}
-
-impl Debug for Linear {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        write!(f, "{}x + {}", self.rel, self.abs)
-    }
-}
diff --git a/src/geom/align.rs b/src/geom/align.rs
new file mode 100644
index 00000000..1030a133
--- /dev/null
+++ b/src/geom/align.rs
@@ -0,0 +1,48 @@
+use super::*;
+
+/// Where to align something along a directed axis.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
+pub enum Align {
+    /// Align at the start of the axis.
+    Start,
+    /// Align in the middle of the axis.
+    Center,
+    /// Align at the end of the axis.
+    End,
+}
+
+impl Align {
+    /// Returns the position of this alignment in the given range.
+    pub fn apply(self, range: Range<Length>) -> Length {
+        match self {
+            Self::Start => range.start,
+            Self::Center => (range.start + range.end) / 2.0,
+            Self::End => range.end,
+        }
+    }
+
+    /// The inverse alignment.
+    pub fn inv(self) -> Self {
+        match self {
+            Self::Start => Self::End,
+            Self::Center => Self::Center,
+            Self::End => Self::Start,
+        }
+    }
+}
+
+impl Default for Align {
+    fn default() -> Self {
+        Self::Start
+    }
+}
+
+impl Display for Align {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.pad(match self {
+            Self::Start => "start",
+            Self::Center => "center",
+            Self::End => "end",
+        })
+    }
+}
diff --git a/src/geom/dir.rs b/src/geom/dir.rs
new file mode 100644
index 00000000..cfcb4c09
--- /dev/null
+++ b/src/geom/dir.rs
@@ -0,0 +1,83 @@
+use super::*;
+
+/// The four directions into which content can be laid out.
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub enum Dir {
+    /// Left to right.
+    LTR,
+    /// Right to left.
+    RTL,
+    /// Top to bottom.
+    TTB,
+    /// Bottom to top.
+    BTT,
+}
+
+impl Dir {
+    /// The side this direction starts at.
+    pub fn start(self) -> Side {
+        match self {
+            Self::LTR => Side::Left,
+            Self::RTL => Side::Right,
+            Self::TTB => Side::Top,
+            Self::BTT => Side::Bottom,
+        }
+    }
+
+    /// The side this direction ends at.
+    pub fn end(self) -> Side {
+        match self {
+            Self::LTR => Side::Right,
+            Self::RTL => Side::Left,
+            Self::TTB => Side::Bottom,
+            Self::BTT => Side::Top,
+        }
+    }
+
+    /// The specific axis this direction belongs to.
+    pub fn axis(self) -> SpecAxis {
+        match self {
+            Self::LTR | Self::RTL => SpecAxis::Horizontal,
+            Self::TTB | Self::BTT => SpecAxis::Vertical,
+        }
+    }
+
+    /// Whether this direction points into the positive coordinate direction.
+    ///
+    /// The positive directions are left-to-right and top-to-bottom.
+    pub fn is_positive(self) -> bool {
+        match self {
+            Self::LTR | Self::TTB => true,
+            Self::RTL | Self::BTT => false,
+        }
+    }
+
+    /// The factor for this direction.
+    ///
+    /// - `1.0` if the direction is positive.
+    /// - `-1.0` if the direction is negative.
+    pub fn factor(self) -> f64 {
+        if self.is_positive() { 1.0 } else { -1.0 }
+    }
+
+    /// The inverse direction.
+    pub fn inv(self) -> Self {
+        match self {
+            Self::LTR => Self::RTL,
+            Self::RTL => Self::LTR,
+            Self::TTB => Self::BTT,
+            Self::BTT => Self::TTB,
+        }
+    }
+}
+
+impl Display for Dir {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.pad(match self {
+            Self::LTR => "ltr",
+            Self::RTL => "rtl",
+            Self::TTB => "ttb",
+            Self::BTT => "btt",
+        })
+    }
+}
diff --git a/src/geom/gen.rs b/src/geom/gen.rs
new file mode 100644
index 00000000..d877713b
--- /dev/null
+++ b/src/geom/gen.rs
@@ -0,0 +1,90 @@
+use super::*;
+
+/// A container with a main and cross component.
+#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
+pub struct Gen<T> {
+    /// The main component.
+    pub main: T,
+    /// The cross component.
+    pub cross: T,
+}
+
+impl<T> Gen<T> {
+    /// Create a new instance from the two components.
+    pub fn new(main: T, cross: T) -> Self {
+        Self { main, cross }
+    }
+}
+
+impl Gen<Length> {
+    /// The zero value.
+    pub const ZERO: Self = Self { main: Length::ZERO, cross: Length::ZERO };
+}
+
+impl<T> Get<GenAxis> for Gen<T> {
+    type Component = T;
+
+    fn get(self, axis: GenAxis) -> T {
+        match axis {
+            GenAxis::Main => self.main,
+            GenAxis::Cross => self.cross,
+        }
+    }
+
+    fn get_mut(&mut self, axis: GenAxis) -> &mut T {
+        match axis {
+            GenAxis::Main => &mut self.main,
+            GenAxis::Cross => &mut self.cross,
+        }
+    }
+}
+
+impl<T> Switch for Gen<T> {
+    type Other = Spec<T>;
+
+    fn switch(self, dirs: Gen<Dir>) -> Self::Other {
+        match dirs.main.axis() {
+            SpecAxis::Horizontal => Spec::new(self.main, self.cross),
+            SpecAxis::Vertical => Spec::new(self.cross, self.main),
+        }
+    }
+}
+
+/// The two generic layouting axes.
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub enum GenAxis {
+    /// The axis pages and paragraphs are set along.
+    Main,
+    /// The axis words and lines are set along.
+    Cross,
+}
+
+impl GenAxis {
+    /// The other axis.
+    pub fn other(self) -> Self {
+        match self {
+            Self::Main => Self::Cross,
+            Self::Cross => Self::Main,
+        }
+    }
+}
+
+impl Switch for GenAxis {
+    type Other = SpecAxis;
+
+    fn switch(self, dirs: Gen<Dir>) -> Self::Other {
+        match self {
+            Self::Main => dirs.main.axis(),
+            Self::Cross => dirs.cross.axis(),
+        }
+    }
+}
+
+impl Display for GenAxis {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.pad(match self {
+            Self::Main => "main",
+            Self::Cross => "cross",
+        })
+    }
+}
diff --git a/src/geom/length.rs b/src/geom/length.rs
new file mode 100644
index 00000000..60ccce2b
--- /dev/null
+++ b/src/geom/length.rs
@@ -0,0 +1,213 @@
+use super::*;
+
+/// An absolute length.
+#[derive(Default, Copy, Clone, PartialEq, PartialOrd)]
+pub struct Length {
+    /// The length in raw units.
+    raw: f64,
+}
+
+impl Length {
+    /// The zero length.
+    pub const ZERO: Self = Self { raw: 0.0 };
+
+    /// Create a length from a number of points.
+    pub fn pt(pt: f64) -> Self {
+        Self::with_unit(pt, Unit::Pt)
+    }
+
+    /// Create a length from a number of millimeters.
+    pub fn mm(mm: f64) -> Self {
+        Self::with_unit(mm, Unit::Mm)
+    }
+
+    /// Create a length from a number of centimeters.
+    pub fn cm(cm: f64) -> Self {
+        Self::with_unit(cm, Unit::Cm)
+    }
+
+    /// Create a length from a number of inches.
+    pub fn inches(inches: f64) -> Self {
+        Self::with_unit(inches, Unit::In)
+    }
+
+    /// Create a length from a number of raw units.
+    pub fn raw(raw: f64) -> Self {
+        Self { raw }
+    }
+
+    /// Convert this to a number of points.
+    pub fn to_pt(self) -> f64 {
+        self.to_unit(Unit::Pt)
+    }
+
+    /// Convert this to a number of millimeters.
+    pub fn to_mm(self) -> f64 {
+        self.to_unit(Unit::Mm)
+    }
+
+    /// Convert this to a number of centimeters.
+    pub fn to_cm(self) -> f64 {
+        self.to_unit(Unit::Cm)
+    }
+
+    /// Convert this to a number of inches.
+    pub fn to_inches(self) -> f64 {
+        self.to_unit(Unit::In)
+    }
+
+    /// Get the value of this length in raw units.
+    pub fn to_raw(self) -> f64 {
+        self.raw
+    }
+
+    /// Create a length from a value in a unit.
+    pub fn with_unit(val: f64, unit: Unit) -> Self {
+        Self { raw: val * unit.raw_scale() }
+    }
+
+    /// Get the value of this length in unit.
+    pub fn to_unit(self, unit: Unit) -> f64 {
+        self.raw / unit.raw_scale()
+    }
+
+    /// The minimum of this and another length.
+    pub fn min(self, other: Self) -> Self {
+        Self { raw: self.raw.min(other.raw) }
+    }
+
+    /// The maximum of this and another length.
+    pub fn max(self, other: Self) -> Self {
+        Self { raw: self.raw.max(other.raw) }
+    }
+}
+
+impl Display for Length {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        // Format small lengths as points and large ones as centimeters.
+        let (val, unit) = if self.to_pt().abs() < 25.0 {
+            (self.to_pt(), Unit::Pt)
+        } else {
+            (self.to_cm(), Unit::Cm)
+        };
+        write!(f, "{:.2}{}", val, unit)
+    }
+}
+
+impl Debug for Length {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        Display::fmt(self, f)
+    }
+}
+
+impl Neg for Length {
+    type Output = Self;
+
+    fn neg(self) -> Self {
+        Self { raw: -self.raw }
+    }
+}
+
+impl Add for Length {
+    type Output = Self;
+
+    fn add(self, other: Self) -> Self {
+        Self { raw: self.raw + other.raw }
+    }
+}
+
+sub_impl!(Length - Length -> Length);
+
+impl Mul<f64> for Length {
+    type Output = Self;
+
+    fn mul(self, other: f64) -> Self {
+        Self { raw: self.raw * other }
+    }
+}
+
+impl Mul<Length> for f64 {
+    type Output = Length;
+
+    fn mul(self, other: Length) -> Length {
+        other * self
+    }
+}
+
+impl Div<f64> for Length {
+    type Output = Self;
+
+    fn div(self, other: f64) -> Self {
+        Self { raw: self.raw / other }
+    }
+}
+
+assign_impl!(Length += Length);
+assign_impl!(Length -= Length);
+assign_impl!(Length *= f64);
+assign_impl!(Length /= f64);
+
+impl Sum for Length {
+    fn sum<I: Iterator<Item = Length>>(iter: I) -> Self {
+        iter.fold(Length::ZERO, Add::add)
+    }
+}
+
+/// Different units of measurement.
+#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
+pub enum Unit {
+    /// Points.
+    Pt,
+    /// Millimeters.
+    Mm,
+    /// Centimeters.
+    Cm,
+    /// Inches.
+    In,
+}
+
+impl Unit {
+    /// How many raw units correspond to a value of `1.0` in this unit.
+    fn raw_scale(self) -> f64 {
+        match self {
+            Unit::Pt => 1.0,
+            Unit::Mm => 2.83465,
+            Unit::Cm => 28.3465,
+            Unit::In => 72.0,
+        }
+    }
+}
+
+impl Display for Unit {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.pad(match self {
+            Unit::Mm => "mm",
+            Unit::Pt => "pt",
+            Unit::Cm => "cm",
+            Unit::In => "in",
+        })
+    }
+}
+
+impl Debug for Unit {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        Display::fmt(self, f)
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_length_formats_correctly() {
+        assert_eq!(Length::pt(-28.34).to_string(), "-1.00cm".to_string());
+        assert_eq!(Length::pt(23.0).to_string(), "23.00pt".to_string());
+        assert_eq!(Length::cm(12.728).to_string(), "12.73cm".to_string());
+    }
+
+    #[test]
+    fn test_length_unit_conversion() {
+        assert!((Length::mm(150.0).to_cm() - 15.0) < 1e-4);
+    }
+}
diff --git a/src/geom/linear.rs b/src/geom/linear.rs
new file mode 100644
index 00000000..2567d264
--- /dev/null
+++ b/src/geom/linear.rs
@@ -0,0 +1,172 @@
+use super::*;
+
+/// A combined relative and absolute length.
+#[derive(Default, Copy, Clone, PartialEq)]
+pub struct Linear {
+    /// The relative part.
+    pub rel: Relative,
+    /// The absolute part.
+    pub abs: Length,
+}
+
+impl Linear {
+    /// The zero linear.
+    pub const ZERO: Linear = Linear { rel: Relative::ZERO, abs: Length::ZERO };
+
+    /// Create a new linear.
+    pub fn new(rel: Relative, abs: Length) -> Self {
+        Self { rel, abs }
+    }
+
+    /// Evaluate the linear length with `one` being `100%` for the relative
+    /// part.
+    pub fn eval(self, one: Length) -> Length {
+        self.rel.eval(one) + self.abs
+    }
+
+    /// Whether this linear's relative component is zero.
+    pub fn is_absolute(self) -> bool {
+        self.rel == Relative::ZERO
+    }
+}
+
+impl Display for Linear {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        write!(f, "{} + {}", self.rel, self.abs)
+    }
+}
+
+impl Debug for Linear {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        Display::fmt(self, f)
+    }
+}
+
+impl From<Length> for Linear {
+    fn from(abs: Length) -> Self {
+        Self { rel: Relative::ZERO, abs }
+    }
+}
+
+impl From<Relative> for Linear {
+    fn from(rel: Relative) -> Self {
+        Self { rel, abs: Length::ZERO }
+    }
+}
+
+impl Neg for Linear {
+    type Output = Self;
+
+    fn neg(self) -> Self {
+        Self { rel: -self.rel, abs: -self.abs }
+    }
+}
+
+impl Add for Linear {
+    type Output = Self;
+
+    fn add(self, other: Self) -> Self {
+        Self {
+            rel: self.rel + other.rel,
+            abs: self.abs + other.abs,
+        }
+    }
+}
+
+impl Add<Relative> for Length {
+    type Output = Linear;
+
+    fn add(self, other: Relative) -> Linear {
+        Linear { rel: other, abs: self }
+    }
+}
+
+impl Add<Length> for Relative {
+    type Output = Linear;
+
+    fn add(self, other: Length) -> Linear {
+        other + self
+    }
+}
+
+impl Add<Length> for Linear {
+    type Output = Self;
+
+    fn add(self, other: Length) -> Self {
+        Self { rel: self.rel, abs: self.abs + other }
+    }
+}
+
+impl Add<Linear> for Length {
+    type Output = Linear;
+
+    fn add(self, other: Linear) -> Linear {
+        other + self
+    }
+}
+
+impl Add<Relative> for Linear {
+    type Output = Self;
+
+    fn add(self, other: Relative) -> Self {
+        Self { rel: self.rel + other, abs: self.abs }
+    }
+}
+
+impl Add<Linear> for Relative {
+    type Output = Linear;
+
+    fn add(self, other: Linear) -> Linear {
+        other + self
+    }
+}
+
+sub_impl!(Linear - Linear -> Linear);
+sub_impl!(Length - Relative -> Linear);
+sub_impl!(Relative - Length -> Linear);
+sub_impl!(Linear - Length -> Linear);
+sub_impl!(Length - Linear -> Linear);
+sub_impl!(Linear - Relative -> Linear);
+sub_impl!(Relative - Linear -> Linear);
+
+impl Mul<f64> for Linear {
+    type Output = Self;
+
+    fn mul(self, other: f64) -> Self {
+        Self {
+            rel: self.rel * other,
+            abs: self.abs * other,
+        }
+    }
+}
+
+impl Mul<Linear> for f64 {
+    type Output = Linear;
+
+    fn mul(self, other: Linear) -> Linear {
+        Linear {
+            rel: self * other.rel,
+            abs: self * other.abs,
+        }
+    }
+}
+
+impl Div<f64> for Linear {
+    type Output = Self;
+
+    fn div(self, other: f64) -> Self {
+        Self {
+            rel: self.rel / other,
+            abs: self.abs / other,
+        }
+    }
+}
+
+assign_impl!(Linear += Linear);
+assign_impl!(Linear += Length);
+assign_impl!(Linear += Relative);
+assign_impl!(Linear -= Linear);
+assign_impl!(Linear -= Length);
+assign_impl!(Linear -= Relative);
+assign_impl!(Linear *= f64);
+assign_impl!(Linear /= f64);
diff --git a/src/geom/macros.rs b/src/geom/macros.rs
new file mode 100644
index 00000000..615eb31c
--- /dev/null
+++ b/src/geom/macros.rs
@@ -0,0 +1,47 @@
+/// Implement the `Sub` trait based on existing `Neg` and `Add` impls.
+macro_rules! sub_impl {
+    ($a:ident - $b:ident -> $c:ident) => {
+        impl Sub<$b> for $a {
+            type Output = $c;
+
+            fn sub(self, other: $b) -> $c {
+                self + -other
+            }
+        }
+    };
+}
+
+/// Implement an assign trait based on an existing non-assign trait.
+macro_rules! assign_impl {
+    ($a:ident += $b:ident) => {
+        impl AddAssign<$b> for $a {
+            fn add_assign(&mut self, other: $b) {
+                *self = *self + other;
+            }
+        }
+    };
+
+    ($a:ident -= $b:ident) => {
+        impl SubAssign<$b> for $a {
+            fn sub_assign(&mut self, other: $b) {
+                *self = *self - other;
+            }
+        }
+    };
+
+    ($a:ident *= $b:ident) => {
+        impl MulAssign<$b> for $a {
+            fn mul_assign(&mut self, other: $b) {
+                *self = *self * other;
+            }
+        }
+    };
+
+    ($a:ident /= $b:ident) => {
+        impl DivAssign<$b> for $a {
+            fn div_assign(&mut self, other: $b) {
+                *self = *self / other;
+            }
+        }
+    };
+}
diff --git a/src/geom/mod.rs b/src/geom/mod.rs
new file mode 100644
index 00000000..c9c3040c
--- /dev/null
+++ b/src/geom/mod.rs
@@ -0,0 +1,53 @@
+//! Geometrical primitivies.
+
+#[macro_use]
+mod macros;
+mod align;
+mod dir;
+mod gen;
+mod length;
+mod linear;
+mod point;
+mod relative;
+mod sides;
+mod size;
+mod spec;
+
+pub use align::*;
+pub use dir::*;
+pub use gen::*;
+pub use length::*;
+pub use linear::*;
+pub use point::*;
+pub use relative::*;
+pub use sides::*;
+pub use size::*;
+pub use spec::*;
+
+use std::fmt::{self, Debug, Display, Formatter};
+use std::iter::Sum;
+use std::ops::*;
+
+/// Generic access to a structure's components.
+pub trait Get<Index> {
+    /// The structure's component type.
+    type Component;
+
+    /// Return the component for the specified index.
+    fn get(self, index: Index) -> Self::Component;
+
+    /// Borrow the component for the specified index mutably.
+    fn get_mut(&mut self, index: Index) -> &mut Self::Component;
+}
+
+/// Switch between the specific and generic representations of a type.
+///
+/// The generic representation deals with main and cross axes while the specific
+/// representation deals with horizontal and vertical axes.
+pub trait Switch {
+    /// The type of the other version.
+    type Other;
+
+    /// The other version of this type based on the current directions.
+    fn switch(self, dirs: Gen<Dir>) -> Self::Other;
+}
diff --git a/src/geom/point.rs b/src/geom/point.rs
new file mode 100644
index 00000000..31b84d81
--- /dev/null
+++ b/src/geom/point.rs
@@ -0,0 +1,102 @@
+use super::*;
+
+/// A point in 2D.
+#[derive(Default, Copy, Clone, PartialEq)]
+pub struct Point {
+    /// The x coordinate.
+    pub x: Length,
+    /// The y coordinate.
+    pub y: Length,
+}
+
+impl Point {
+    /// The origin point.
+    pub const ZERO: Self = Self { x: Length::ZERO, y: Length::ZERO };
+
+    /// Create a new point from x and y coordinate.
+    pub fn new(x: Length, y: Length) -> Self {
+        Self { x, y }
+    }
+}
+
+impl Get<SpecAxis> for Point {
+    type Component = Length;
+
+    fn get(self, axis: SpecAxis) -> Length {
+        match axis {
+            SpecAxis::Horizontal => self.x,
+            SpecAxis::Vertical => self.y,
+        }
+    }
+
+    fn get_mut(&mut self, axis: SpecAxis) -> &mut Length {
+        match axis {
+            SpecAxis::Horizontal => &mut self.x,
+            SpecAxis::Vertical => &mut self.y,
+        }
+    }
+}
+
+impl Switch for Point {
+    type Other = Gen<Length>;
+
+    fn switch(self, dirs: Gen<Dir>) -> Self::Other {
+        match dirs.main.axis() {
+            SpecAxis::Horizontal => Gen::new(self.x, self.y),
+            SpecAxis::Vertical => Gen::new(self.y, self.x),
+        }
+    }
+}
+
+impl Debug for Point {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        write!(f, "({}, {})", self.x, self.y)
+    }
+}
+
+impl Neg for Point {
+    type Output = Self;
+
+    fn neg(self) -> Self {
+        Self { x: -self.x, y: -self.y }
+    }
+}
+
+impl Add for Point {
+    type Output = Self;
+
+    fn add(self, other: Self) -> Self {
+        Self { x: self.x + other.x, y: self.y + other.y }
+    }
+}
+
+sub_impl!(Point - Point -> Point);
+
+impl Mul<f64> for Point {
+    type Output = Self;
+
+    fn mul(self, other: f64) -> Self {
+        Self { x: self.x * other, y: self.y * other }
+    }
+}
+
+impl Mul<Point> for f64 {
+    type Output = Point;
+
+    fn mul(self, other: Point) -> Point {
+        other * self
+    }
+}
+
+impl Div<f64> for Point {
+    type Output = Self;
+
+    fn div(self, other: f64) -> Self {
+        Self { x: self.x / other, y: self.y / other }
+    }
+}
+
+assign_impl!(Point += Point);
+assign_impl!(Point -= Point);
+assign_impl!(Point *= f64);
+assign_impl!(Point /= f64);
diff --git a/src/geom/relative.rs b/src/geom/relative.rs
new file mode 100644
index 00000000..037c83dc
--- /dev/null
+++ b/src/geom/relative.rs
@@ -0,0 +1,92 @@
+use super::*;
+
+/// A relative length.
+///
+/// _Note_: `50%` is represented as `0.5` here, but stored as `50.0` in the
+/// corresponding [literal].
+///
+/// [literal]: ../syntax/ast/enum.Lit.html#variant.Percent
+#[derive(Default, Copy, Clone, PartialEq, PartialOrd)]
+pub struct Relative(f64);
+
+impl Relative {
+    /// A ratio of `0%` represented as `0.0`.
+    pub const ZERO: Self = Self(0.0);
+
+    /// A ratio of `100%` represented as `1.0`.
+    pub const ONE: Self = Self(1.0);
+
+    /// Create a new relative value.
+    pub fn new(ratio: f64) -> Self {
+        Self(ratio)
+    }
+
+    /// Get the underlying ratio.
+    pub fn get(self) -> f64 {
+        self.0
+    }
+
+    /// Evaluate the relative length with `one` being `100%`.
+    pub fn eval(self, one: Length) -> Length {
+        self.get() * one
+    }
+}
+
+impl Display for Relative {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        write!(f, "{:.2}%", self.0)
+    }
+}
+
+impl Debug for Relative {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        Display::fmt(self, f)
+    }
+}
+
+impl Neg for Relative {
+    type Output = Self;
+
+    fn neg(self) -> Self {
+        Self(-self.0)
+    }
+}
+
+impl Add for Relative {
+    type Output = Self;
+
+    fn add(self, other: Self) -> Self {
+        Self(self.0 + other.0)
+    }
+}
+
+sub_impl!(Relative - Relative -> Relative);
+
+impl Mul<f64> for Relative {
+    type Output = Self;
+
+    fn mul(self, other: f64) -> Self {
+        Self(self.0 * other)
+    }
+}
+
+impl Mul<Relative> for f64 {
+    type Output = Relative;
+
+    fn mul(self, other: Relative) -> Relative {
+        other * self
+    }
+}
+
+impl Div<f64> for Relative {
+    type Output = Self;
+
+    fn div(self, other: f64) -> Self {
+        Self(self.0 / other)
+    }
+}
+
+assign_impl!(Relative += Relative);
+assign_impl!(Relative -= Relative);
+assign_impl!(Relative *= f64);
+assign_impl!(Relative /= f64);
diff --git a/src/geom/sides.rs b/src/geom/sides.rs
new file mode 100644
index 00000000..770fad58
--- /dev/null
+++ b/src/geom/sides.rs
@@ -0,0 +1,101 @@
+use super::*;
+
+/// A container with left, top, right and bottom components.
+#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
+pub struct Sides<T> {
+    /// The value for the left side.
+    pub left: T,
+    /// The value for the top side.
+    pub top: T,
+    /// The value for the right side.
+    pub right: T,
+    /// The value for the bottom side.
+    pub bottom: T,
+}
+
+impl<T> Sides<T> {
+    /// Create a new box from four sizes.
+    pub fn new(left: T, top: T, right: T, bottom: T) -> Self {
+        Self { left, top, right, bottom }
+    }
+
+    /// Create an instance with all four components set to the same `value`.
+    pub fn uniform(value: T) -> Self
+    where
+        T: Clone,
+    {
+        Self {
+            left: value.clone(),
+            top: value.clone(),
+            right: value.clone(),
+            bottom: value,
+        }
+    }
+}
+
+impl Sides<Linear> {
+    /// Evaluate the linear values in this container.
+    pub fn eval(self, size: Size) -> Sides<Length> {
+        Sides {
+            left: self.left.eval(size.width),
+            top: self.top.eval(size.height),
+            right: self.right.eval(size.width),
+            bottom: self.bottom.eval(size.height),
+        }
+    }
+}
+
+impl Sides<Length> {
+    /// A size with `left` and `right` summed into `width`, and `top` and
+    /// `bottom` summed into `height`.
+    pub fn size(self) -> Size {
+        Size::new(self.left + self.right, self.top + self.bottom)
+    }
+}
+
+impl<T> Get<Side> for Sides<T> {
+    type Component = T;
+
+    fn get(self, side: Side) -> T {
+        match side {
+            Side::Left => self.left,
+            Side::Top => self.top,
+            Side::Right => self.right,
+            Side::Bottom => self.bottom,
+        }
+    }
+
+    fn get_mut(&mut self, side: Side) -> &mut T {
+        match side {
+            Side::Left => &mut self.left,
+            Side::Top => &mut self.top,
+            Side::Right => &mut self.right,
+            Side::Bottom => &mut self.bottom,
+        }
+    }
+}
+
+/// The four sides of objects.
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub enum Side {
+    /// The left side.
+    Left,
+    /// The top side.
+    Top,
+    /// The right side.
+    Right,
+    /// The bottom side.
+    Bottom,
+}
+
+impl Side {
+    /// The opposite side.
+    pub fn inv(self) -> Self {
+        match self {
+            Self::Left => Self::Right,
+            Self::Top => Self::Bottom,
+            Self::Right => Self::Left,
+            Self::Bottom => Self::Top,
+        }
+    }
+}
diff --git a/src/geom/size.rs b/src/geom/size.rs
new file mode 100644
index 00000000..8a3951f7
--- /dev/null
+++ b/src/geom/size.rs
@@ -0,0 +1,119 @@
+use super::*;
+
+/// A size in 2D.
+#[derive(Default, Copy, Clone, PartialEq)]
+pub struct Size {
+    /// The width.
+    pub width: Length,
+    /// The height.
+    pub height: Length,
+}
+
+impl Size {
+    /// The zero size.
+    pub const ZERO: Self = Self {
+        width: Length::ZERO,
+        height: Length::ZERO,
+    };
+
+    /// Create a new size from width and height.
+    pub fn new(width: Length, height: Length) -> Self {
+        Self { width, height }
+    }
+
+    /// Whether the other size fits into this one (smaller width and height).
+    pub fn fits(self, other: Self) -> bool {
+        self.width >= other.width && self.height >= other.height
+    }
+}
+
+impl Get<SpecAxis> for Size {
+    type Component = Length;
+
+    fn get(self, axis: SpecAxis) -> Length {
+        match axis {
+            SpecAxis::Horizontal => self.width,
+            SpecAxis::Vertical => self.height,
+        }
+    }
+
+    fn get_mut(&mut self, axis: SpecAxis) -> &mut Length {
+        match axis {
+            SpecAxis::Horizontal => &mut self.width,
+            SpecAxis::Vertical => &mut self.height,
+        }
+    }
+}
+
+impl Switch for Size {
+    type Other = Gen<Length>;
+
+    fn switch(self, dirs: Gen<Dir>) -> Self::Other {
+        match dirs.main.axis() {
+            SpecAxis::Horizontal => Gen::new(self.width, self.height),
+            SpecAxis::Vertical => Gen::new(self.height, self.width),
+        }
+    }
+}
+
+impl Debug for Size {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        write!(f, "({} x {})", self.width, self.height)
+    }
+}
+
+impl Neg for Size {
+    type Output = Self;
+
+    fn neg(self) -> Self {
+        Self { width: -self.width, height: -self.height }
+    }
+}
+
+impl Add for Size {
+    type Output = Self;
+
+    fn add(self, other: Self) -> Self {
+        Self {
+            width: self.width + other.width,
+            height: self.height + other.height,
+        }
+    }
+}
+
+sub_impl!(Size - Size -> Size);
+
+impl Mul<f64> for Size {
+    type Output = Self;
+
+    fn mul(self, other: f64) -> Self {
+        Self {
+            width: self.width * other,
+            height: self.height * other,
+        }
+    }
+}
+
+impl Mul<Size> for f64 {
+    type Output = Size;
+
+    fn mul(self, other: Size) -> Size {
+        other * self
+    }
+}
+
+impl Div<f64> for Size {
+    type Output = Self;
+
+    fn div(self, other: f64) -> Self {
+        Self {
+            width: self.width / other,
+            height: self.height / other,
+        }
+    }
+}
+
+assign_impl!(Size -= Size);
+assign_impl!(Size += Size);
+assign_impl!(Size *= f64);
+assign_impl!(Size /= f64);
diff --git a/src/geom/spec.rs b/src/geom/spec.rs
new file mode 100644
index 00000000..8a9519bc
--- /dev/null
+++ b/src/geom/spec.rs
@@ -0,0 +1,105 @@
+use super::*;
+
+/// A container with a horizontal and vertical component.
+#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
+pub struct Spec<T> {
+    /// The horizontal component.
+    pub horizontal: T,
+    /// The vertical component.
+    pub vertical: T,
+}
+
+impl<T> Spec<T> {
+    /// Create a new instance from the two components.
+    pub fn new(horizontal: T, vertical: T) -> Self {
+        Self { horizontal, vertical }
+    }
+}
+
+impl Spec<Length> {
+    /// The zero value.
+    pub const ZERO: Self = Self {
+        horizontal: Length::ZERO,
+        vertical: Length::ZERO,
+    };
+
+    /// Convert to a point.
+    pub fn to_point(self) -> Point {
+        Point::new(self.horizontal, self.vertical)
+    }
+
+    /// Convert to a size.
+    pub fn to_size(self) -> Size {
+        Size::new(self.horizontal, self.vertical)
+    }
+}
+
+impl<T> Get<SpecAxis> for Spec<T> {
+    type Component = T;
+
+    fn get(self, axis: SpecAxis) -> T {
+        match axis {
+            SpecAxis::Horizontal => self.horizontal,
+            SpecAxis::Vertical => self.vertical,
+        }
+    }
+
+    fn get_mut(&mut self, axis: SpecAxis) -> &mut T {
+        match axis {
+            SpecAxis::Horizontal => &mut self.horizontal,
+            SpecAxis::Vertical => &mut self.vertical,
+        }
+    }
+}
+
+impl<T> Switch for Spec<T> {
+    type Other = Gen<T>;
+
+    fn switch(self, dirs: Gen<Dir>) -> Self::Other {
+        match dirs.main.axis() {
+            SpecAxis::Horizontal => Gen::new(self.horizontal, self.vertical),
+            SpecAxis::Vertical => Gen::new(self.vertical, self.horizontal),
+        }
+    }
+}
+
+/// The two specific layouting axes.
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub enum SpecAxis {
+    /// The vertical layouting axis.
+    Vertical,
+    /// The horizontal layouting axis.
+    Horizontal,
+}
+
+impl SpecAxis {
+    /// The other axis.
+    pub fn other(self) -> Self {
+        match self {
+            Self::Horizontal => Self::Vertical,
+            Self::Vertical => Self::Horizontal,
+        }
+    }
+}
+
+impl Switch for SpecAxis {
+    type Other = GenAxis;
+
+    fn switch(self, dirs: Gen<Dir>) -> Self::Other {
+        if self == dirs.main.axis() {
+            GenAxis::Main
+        } else {
+            debug_assert_eq!(self, dirs.cross.axis());
+            GenAxis::Cross
+        }
+    }
+}
+
+impl Display for SpecAxis {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.pad(match self {
+            Self::Vertical => "vertical",
+            Self::Horizontal => "horizontal",
+        })
+    }
+}
diff --git a/src/layout/nodes/document.rs b/src/layout/document.rs
index 5c7a2410..c2d7b38b 100644
--- a/src/layout/nodes/document.rs
+++ b/src/layout/document.rs
@@ -1,6 +1,6 @@
 use super::*;
 
-/// The top-level layouting node.
+/// The top-level layout node.
 #[derive(Debug, Clone, PartialEq)]
 pub struct Document {
     pub runs: Vec<Pages>,
diff --git a/src/layout/nodes/fixed.rs b/src/layout/fixed.rs
index 0d438879..0d438879 100644
--- a/src/layout/nodes/fixed.rs
+++ b/src/layout/fixed.rs
diff --git a/src/layout/mod.rs b/src/layout/mod.rs
index bfd633d8..2368c441 100644
--- a/src/layout/mod.rs
+++ b/src/layout/mod.rs
@@ -1,17 +1,28 @@
 //! Layouting of documents.
 
-pub mod nodes;
-pub mod primitive;
-
-pub use primitive::*;
+mod document;
+mod fixed;
+mod node;
+mod pad;
+mod par;
+mod spacing;
+mod stack;
+mod text;
 
 use async_trait::async_trait;
 
 use crate::font::SharedFontLoader;
-use crate::geom::{Point, Rect, Size, SizeExt};
+use crate::geom::*;
 use crate::shaping::Shaped;
 
-use nodes::Document;
+pub use document::*;
+pub use fixed::*;
+pub use node::*;
+pub use pad::*;
+pub use par::*;
+pub use spacing::*;
+pub use stack::*;
+pub use text::*;
 
 /// Layout a document and return the produced layouts.
 pub async fn layout(document: &Document, loader: SharedFontLoader) -> Vec<BoxLayout> {
@@ -53,9 +64,9 @@ pub trait Layout {
 #[derive(Debug, Clone, PartialEq)]
 pub enum LayoutItem {
     /// Spacing that should be added to the parent.
-    Spacing(f64),
+    Spacing(Length),
     /// A box that should be aligned in the parent.
-    Box(BoxLayout, Gen2<GenAlign>),
+    Box(BoxLayout, Gen<Align>),
 }
 
 /// The constraints for layouting a single node.
@@ -101,7 +112,7 @@ impl BoxLayout {
     /// given position.
     pub fn push_layout(&mut self, pos: Point, more: Self) {
         for (subpos, element) in more.elements {
-            self.push(pos + subpos.to_vec2(), element);
+            self.push(pos + subpos, element);
         }
     }
 }
diff --git a/src/layout/nodes/mod.rs b/src/layout/node.rs
index a304e63c..3230621f 100644
--- a/src/layout/nodes/mod.rs
+++ b/src/layout/node.rs
@@ -1,27 +1,9 @@
 //! Layout nodes.
 
-mod document;
-mod fixed;
-mod pad;
-mod par;
-mod spacing;
-mod stack;
-mod text;
-
-pub use document::*;
-pub use fixed::*;
-pub use pad::*;
-pub use par::*;
-pub use spacing::*;
-pub use stack::*;
-pub use text::*;
-
 use std::any::Any;
 use std::fmt::{self, Debug, Formatter};
 use std::ops::Deref;
 
-use async_trait::async_trait;
-
 use super::*;
 
 /// A self-contained, styled layout node.
diff --git a/src/layout/nodes/pad.rs b/src/layout/pad.rs
index 10a9e2c6..2e1817b7 100644
--- a/src/layout/nodes/pad.rs
+++ b/src/layout/pad.rs
@@ -21,8 +21,8 @@ impl Layout for Pad {
                     .spaces
                     .into_iter()
                     .map(|space| LayoutSpace {
-                        base: space.base + self.padding.insets(space.base).size(),
-                        size: space.size + self.padding.insets(space.size).size(),
+                        base: space.base - self.padding.eval(space.base).size(),
+                        size: space.size - self.padding.eval(space.size).size(),
                     })
                     .collect(),
                 repeat: constraints.repeat,
@@ -31,11 +31,11 @@ impl Layout for Pad {
             .into_iter()
             .map(|item| match item {
                 LayoutItem::Box(boxed, align) => {
-                    let padding = self.padding.insets(boxed.size);
-                    let padded = boxed.size - padding.size();
+                    let padding = self.padding.eval(boxed.size);
+                    let padded = boxed.size + padding.size();
 
                     let mut outer = BoxLayout::new(padded);
-                    let start = Point::new(-padding.x0, -padding.y0);
+                    let start = Point::new(padding.left, padding.top);
                     outer.push_layout(start, boxed);
 
                     LayoutItem::Box(outer, align)
diff --git a/src/layout/nodes/par.rs b/src/layout/par.rs
index 082ab963..2a139760 100644
--- a/src/layout/nodes/par.rs
+++ b/src/layout/par.rs
@@ -7,11 +7,11 @@ use super::*;
 /// the main axis by the height of the previous line plus extra line spacing.
 #[derive(Debug, Clone, PartialEq)]
 pub struct Par {
-    pub dirs: Gen2<Dir>,
-    pub line_spacing: f64,
+    pub dirs: Gen<Dir>,
+    pub line_spacing: Length,
     pub children: Vec<LayoutNode>,
-    pub aligns: Gen2<GenAlign>,
-    pub expand: Spec2<bool>,
+    pub aligns: Gen<Align>,
+    pub expand: Spec<bool>,
 }
 
 #[async_trait(?Send)]
@@ -73,17 +73,17 @@ struct LineLayouter {
 #[derive(Debug, Clone)]
 struct LineContext {
     /// The layout directions.
-    dirs: Gen2<Dir>,
+    dirs: Gen<Dir>,
     /// The spaces to layout into.
     spaces: Vec<LayoutSpace>,
     /// Whether to spill over into copies of the last space or finish layouting
     /// when the last space is used up.
     repeat: bool,
     /// The spacing to be inserted between each pair of lines.
-    line_spacing: f64,
+    line_spacing: Length,
     /// Whether to expand the size of the resulting layout to the full size of
     /// this space or to shrink it to fit the content.
-    expand: Spec2<bool>,
+    expand: Spec<bool>,
 }
 
 impl LineLayouter {
@@ -102,7 +102,7 @@ impl LineLayouter {
     }
 
     /// Add a layout.
-    fn push_box(&mut self, layout: BoxLayout, aligns: Gen2<GenAlign>) {
+    fn push_box(&mut self, layout: BoxLayout, aligns: Gen<Align>) {
         let dirs = self.ctx.dirs;
         if let Some(prev) = self.run.aligns {
             if aligns.main != prev.main {
@@ -124,9 +124,9 @@ impl LineLayouter {
 
                 // FIXME: Alignment in non-expanding parent.
                 rest_run.usable = Some(match aligns.cross {
-                    GenAlign::Start => unreachable!("start > x"),
-                    GenAlign::Center => usable - 2.0 * self.run.size.cross,
-                    GenAlign::End => usable - self.run.size.cross,
+                    Align::Start => unreachable!("start > x"),
+                    Align::Center => usable - 2.0 * self.run.size.cross,
+                    Align::End => usable - self.run.size.cross,
                 });
 
                 self.finish_line();
@@ -160,7 +160,7 @@ impl LineLayouter {
     }
 
     /// Add spacing to the line.
-    fn push_spacing(&mut self, mut spacing: f64) {
+    fn push_spacing(&mut self, mut spacing: Length) {
         spacing = spacing.min(self.usable().cross);
         self.run.size.cross += spacing;
     }
@@ -169,7 +169,7 @@ impl LineLayouter {
     ///
     /// This specifies how much more would fit before a line break would be
     /// needed.
-    fn usable(&self) -> Gen2<f64> {
+    fn usable(&self) -> Gen<Length> {
         // The base is the usable space of the stack layouter.
         let mut usable = self.stack.usable().switch(self.ctx.dirs);
 
@@ -192,7 +192,7 @@ impl LineLayouter {
 
     /// Whether the currently set line is empty.
     fn line_is_empty(&self) -> bool {
-        self.run.size == Gen2::ZERO && self.run.layouts.is_empty()
+        self.run.size == Gen::ZERO && self.run.layouts.is_empty()
     }
 
     /// Finish everything up and return the final collection of boxes.
@@ -224,7 +224,7 @@ impl LineLayouter {
                 self.run.size.cross - offset - child.size.get(dirs.cross.axis())
             };
 
-            let pos = Gen2::new(0.0, cross).switch(dirs).to_point();
+            let pos = Gen::new(Length::ZERO, cross).switch(dirs).to_point();
             layout.push_layout(pos, child);
         }
 
@@ -244,25 +244,25 @@ impl LineLayouter {
 /// multiple runs with different alignments.
 struct LineRun {
     /// The so-far accumulated items of the run.
-    layouts: Vec<(f64, BoxLayout)>,
+    layouts: Vec<(Length, BoxLayout)>,
     /// The summed width and maximal height of the run.
-    size: Gen2<f64>,
+    size: Gen<Length>,
     /// The alignment of all layouts in the line.
     ///
     /// When a new run is created the alignment is yet to be determined and
     /// `None` as such. Once a layout is added, its alignment decides the
     /// alignment for the whole run.
-    aligns: Option<Gen2<GenAlign>>,
+    aligns: Option<Gen<Align>>,
     /// The amount of cross-space left by another run on the same line or `None`
     /// if this is the only run so far.
-    usable: Option<f64>,
+    usable: Option<Length>,
 }
 
 impl LineRun {
     fn new() -> Self {
         Self {
             layouts: vec![],
-            size: Gen2::ZERO,
+            size: Gen::ZERO,
             aligns: None,
             usable: None,
         }
@@ -283,7 +283,7 @@ pub(super) struct StackLayouter {
 #[derive(Debug, Clone)]
 pub(super) struct StackContext {
     /// The layouting directions.
-    pub dirs: Gen2<Dir>,
+    pub dirs: Gen<Dir>,
     /// The spaces to layout into.
     pub spaces: Vec<LayoutSpace>,
     /// Whether to spill over into copies of the last space or finish layouting
@@ -291,7 +291,7 @@ pub(super) struct StackContext {
     pub repeat: bool,
     /// Whether to expand the size of the resulting layout to the full size of
     /// this space or to shrink it to fit the content.
-    pub expand: Spec2<bool>,
+    pub expand: Spec<bool>,
 }
 
 impl StackLayouter {
@@ -306,7 +306,7 @@ impl StackLayouter {
     }
 
     /// Add a layout to the stack.
-    pub fn push_box(&mut self, layout: BoxLayout, aligns: Gen2<GenAlign>) {
+    pub fn push_box(&mut self, layout: BoxLayout, aligns: Gen<Align>) {
         // If the alignment cannot be fitted in this space, finish it.
         //
         // TODO: Issue warning for non-fitting alignment in non-repeating
@@ -331,20 +331,20 @@ impl StackLayouter {
     }
 
     /// Add spacing to the stack.
-    pub fn push_spacing(&mut self, mut spacing: f64) {
+    pub fn push_spacing(&mut self, mut spacing: Length) {
         // Reduce the spacing such that it definitely fits.
         let axis = self.ctx.dirs.main.axis();
         spacing = spacing.min(self.space.usable.get(axis));
 
-        let size = Gen2::new(spacing, 0.0);
+        let size = Gen::new(spacing, Length::ZERO);
         self.update_metrics(size);
         self.space.layouts.push((
             BoxLayout::new(size.switch(self.ctx.dirs).to_size()),
-            Gen2::default(),
+            Gen::default(),
         ));
     }
 
-    fn update_metrics(&mut self, added: Gen2<f64>) {
+    fn update_metrics(&mut self, added: Gen<Length>) {
         let mut used = self.space.used.switch(self.ctx.dirs);
         used.cross = used.cross.max(added.cross);
         used.main += added.main;
@@ -398,11 +398,7 @@ impl StackLayouter {
     /// Finish active current space and start a new one.
     pub fn finish_space(&mut self, hard: bool) {
         let dirs = self.ctx.dirs;
-
-        // ------------------------------------------------------------------ //
-        // Step 1: Determine the full size of the space.
-        // (Mostly done already while collecting the boxes, but here we
-        //  expand if necessary.)
+        let main = dirs.main.axis();
 
         let space = self.ctx.spaces[self.space.index];
         let layout_size = {
@@ -416,64 +412,44 @@ impl StackLayouter {
             used_size
         };
 
-        let mut layout = BoxLayout::new(layout_size);
+        let mut sum = Length::ZERO;
+        let mut sums = Vec::with_capacity(self.space.layouts.len() + 1);
 
-        // ------------------------------------------------------------------ //
-        // Step 2: Forward pass. Create a bounding box for each layout in which
-        // it will be aligned. Then, go forwards through the boxes and remove
-        // what is taken by previous layouts from the following layouts.
-
-        let mut bounds = vec![];
-        let mut bound = Rect {
-            x0: 0.0,
-            y0: 0.0,
-            x1: layout_size.width,
-            y1: layout_size.height,
-        };
-
-        for (layout, _) in &self.space.layouts {
-            // First, store the bounds calculated so far (which were reduced
-            // by the predecessors of this layout) as the initial bounding box
-            // of this layout.
-            bounds.push(bound);
-
-            // Then, reduce the bounding box for the following layouts. This
-            // layout uses up space from the origin to the end. Thus, it reduces
-            // the usable space for following layouts at its origin by its
-            // main-axis extent.
-            *bound.get_mut(dirs.main.start()) +=
-                dirs.main.factor() * layout.size.get(dirs.main.axis());
+        for (boxed, _) in &self.space.layouts {
+            sums.push(sum);
+            sum += boxed.size.get(main);
         }
 
-        // ------------------------------------------------------------------ //
-        // Step 3: Backward pass. Reduce the bounding boxes from the previous
-        // layouts by what is taken by the following ones.
-
-        let mut main_extent = 0.0;
-        for (child, bound) in self.space.layouts.iter().zip(&mut bounds).rev() {
-            let (layout, _) = child;
+        sums.push(sum);
 
-            // Reduce the bounding box of this layout by the following one's
-            // main-axis extents.
-            *bound.get_mut(dirs.main.end()) -= dirs.main.factor() * main_extent;
+        let mut layout = BoxLayout::new(layout_size);
+        let used = layout_size.switch(dirs);
 
-            // And then, include this layout's main-axis extent.
-            main_extent += layout.size.get(dirs.main.axis());
-        }
+        let children = std::mem::take(&mut self.space.layouts);
+        for (i, (boxed, aligns)) in children.into_iter().enumerate() {
+            let size = boxed.size.switch(dirs);
+
+            let before = sums[i];
+            let after = sum - sums[i + 1];
+            let main_len = used.main - size.main;
+            let main_range = if dirs.main.is_positive() {
+                before .. main_len - after
+            } else {
+                main_len - before .. after
+            };
 
-        // ------------------------------------------------------------------ //
-        // Step 4: Align each layout in its bounding box and collect everything
-        // into a single finished layout.
+            let cross_len = used.cross - size.cross;
+            let cross_range = if dirs.cross.is_positive() {
+                Length::ZERO .. cross_len
+            } else {
+                cross_len .. Length::ZERO
+            };
 
-        let children = std::mem::take(&mut self.space.layouts);
-        for ((child, aligns), bound) in children.into_iter().zip(bounds) {
-            // Align the child in its own bounds.
-            let local =
-                bound.size().anchor(dirs, aligns) - child.size.anchor(dirs, aligns);
+            let main = aligns.main.apply(main_range);
+            let cross = aligns.cross.apply(cross_range);
+            let pos = Gen::new(main, cross).switch(dirs).to_point();
 
-            // Make the local position in the bounds global.
-            let pos = bound.origin() + local;
-            layout.push_layout(pos, child);
+            layout.push_layout(pos, boxed);
         }
 
         self.layouts.push(layout);
@@ -503,7 +479,7 @@ pub(super) struct Space {
     /// Whether to include a layout for this space even if it would be empty.
     hard: bool,
     /// The so-far accumulated layouts.
-    layouts: Vec<(BoxLayout, Gen2<GenAlign>)>,
+    layouts: Vec<(BoxLayout, Gen<Align>)>,
     /// The full size of this space.
     size: Size,
     /// The used size of this space.
@@ -511,7 +487,7 @@ pub(super) struct Space {
     /// The remaining space.
     usable: Size,
     /// Which alignments for new boxes are still allowed.
-    pub(super) allowed_align: GenAlign,
+    pub(super) allowed_align: Align,
 }
 
 impl Space {
@@ -523,7 +499,7 @@ impl Space {
             size,
             used: Size::ZERO,
             usable: size,
-            allowed_align: GenAlign::Start,
+            allowed_align: Align::Start,
         }
     }
 }
diff --git a/src/layout/primitive.rs b/src/layout/primitive.rs
deleted file mode 100644
index 30bd9363..00000000
--- a/src/layout/primitive.rs
+++ /dev/null
@@ -1,510 +0,0 @@
-//! Layouting primitives.
-
-use std::fmt::{self, Display, Formatter};
-use std::ops::Range;
-
-use crate::geom::{Insets, Linear, Point, Size, Vec2};
-
-/// Generic access to a structure's components.
-pub trait Get<Index> {
-    /// The structure's component type.
-    type Component;
-
-    /// Return the component for the specified index.
-    fn get(self, index: Index) -> Self::Component;
-
-    /// Borrow the component for the specified index mutably.
-    fn get_mut(&mut self, index: Index) -> &mut Self::Component;
-}
-
-/// Switch between the specific and generic representations of a type.
-///
-/// The generic representation deals with main and cross axes while the specific
-/// representation deals with horizontal and vertical axes.
-pub trait Switch {
-    /// The type of the other version.
-    type Other;
-
-    /// The other version of this type based on the current directions.
-    fn switch(self, dirs: Gen2<Dir>) -> Self::Other;
-}
-
-/// The four directions into which content can be laid out.
-#[derive(Debug, Copy, Clone, Eq, PartialEq)]
-pub enum Dir {
-    /// Left to right.
-    LTR,
-    /// Right to left.
-    RTL,
-    /// Top to bottom.
-    TTB,
-    /// Bottom to top.
-    BTT,
-}
-
-impl Dir {
-    /// The specific axis this direction belongs to.
-    pub fn axis(self) -> SpecAxis {
-        match self {
-            Self::LTR | Self::RTL => SpecAxis::Horizontal,
-            Self::TTB | Self::BTT => SpecAxis::Vertical,
-        }
-    }
-
-    /// The side this direction starts at.
-    pub fn start(self) -> Side {
-        match self {
-            Self::LTR => Side::Left,
-            Self::RTL => Side::Right,
-            Self::TTB => Side::Top,
-            Self::BTT => Side::Bottom,
-        }
-    }
-
-    /// The side this direction ends at.
-    pub fn end(self) -> Side {
-        match self {
-            Self::LTR => Side::Right,
-            Self::RTL => Side::Left,
-            Self::TTB => Side::Bottom,
-            Self::BTT => Side::Top,
-        }
-    }
-
-    /// Whether this direction points into the positive coordinate direction.
-    ///
-    /// The positive directions are left-to-right and top-to-bottom.
-    pub fn is_positive(self) -> bool {
-        match self {
-            Self::LTR | Self::TTB => true,
-            Self::RTL | Self::BTT => false,
-        }
-    }
-
-    /// The factor for this direction.
-    ///
-    /// - `1.0` if the direction is positive.
-    /// - `-1.0` if the direction is negative.
-    pub fn factor(self) -> f64 {
-        if self.is_positive() { 1.0 } else { -1.0 }
-    }
-
-    /// The inverse direction.
-    pub fn inv(self) -> Self {
-        match self {
-            Self::LTR => Self::RTL,
-            Self::RTL => Self::LTR,
-            Self::TTB => Self::BTT,
-            Self::BTT => Self::TTB,
-        }
-    }
-}
-
-impl Display for Dir {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.pad(match self {
-            Self::LTR => "ltr",
-            Self::RTL => "rtl",
-            Self::TTB => "ttb",
-            Self::BTT => "btt",
-        })
-    }
-}
-
-/// A generic container with two components for the two generic axes.
-#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
-pub struct Gen2<T> {
-    /// The main component.
-    pub main: T,
-    /// The cross component.
-    pub cross: T,
-}
-
-impl<T> Gen2<T> {
-    /// Create a new instance from the two components.
-    pub fn new(main: T, cross: T) -> Self {
-        Self { main, cross }
-    }
-}
-
-impl Gen2<f64> {
-    /// The instance that has both components set to zero.
-    pub const ZERO: Self = Self { main: 0.0, cross: 0.0 };
-}
-
-impl<T> Get<GenAxis> for Gen2<T> {
-    type Component = T;
-
-    fn get(self, axis: GenAxis) -> T {
-        match axis {
-            GenAxis::Main => self.main,
-            GenAxis::Cross => self.cross,
-        }
-    }
-
-    fn get_mut(&mut self, axis: GenAxis) -> &mut T {
-        match axis {
-            GenAxis::Main => &mut self.main,
-            GenAxis::Cross => &mut self.cross,
-        }
-    }
-}
-
-impl<T> Switch for Gen2<T> {
-    type Other = Spec2<T>;
-
-    fn switch(self, dirs: Gen2<Dir>) -> Self::Other {
-        match dirs.main.axis() {
-            SpecAxis::Horizontal => Spec2::new(self.main, self.cross),
-            SpecAxis::Vertical => Spec2::new(self.cross, self.main),
-        }
-    }
-}
-
-/// A generic container with two components for the two specific axes.
-#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
-pub struct Spec2<T> {
-    /// The horizontal component.
-    pub horizontal: T,
-    /// The vertical component.
-    pub vertical: T,
-}
-
-impl<T> Spec2<T> {
-    /// Create a new instance from the two components.
-    pub fn new(horizontal: T, vertical: T) -> Self {
-        Self { horizontal, vertical }
-    }
-}
-
-impl Spec2<f64> {
-    /// The instance that has both components set to zero.
-    pub const ZERO: Self = Self { horizontal: 0.0, vertical: 0.0 };
-
-    /// Convert to a 2D vector.
-    pub fn to_vec2(self) -> Vec2 {
-        Vec2::new(self.horizontal, self.vertical)
-    }
-
-    /// Convert to a point.
-    pub fn to_point(self) -> Point {
-        Point::new(self.horizontal, self.vertical)
-    }
-
-    /// Convert to a size.
-    pub fn to_size(self) -> Size {
-        Size::new(self.horizontal, self.vertical)
-    }
-}
-
-impl<T> Get<SpecAxis> for Spec2<T> {
-    type Component = T;
-
-    fn get(self, axis: SpecAxis) -> T {
-        match axis {
-            SpecAxis::Horizontal => self.horizontal,
-            SpecAxis::Vertical => self.vertical,
-        }
-    }
-
-    fn get_mut(&mut self, axis: SpecAxis) -> &mut T {
-        match axis {
-            SpecAxis::Horizontal => &mut self.horizontal,
-            SpecAxis::Vertical => &mut self.vertical,
-        }
-    }
-}
-
-impl<T> Switch for Spec2<T> {
-    type Other = Gen2<T>;
-
-    fn switch(self, dirs: Gen2<Dir>) -> Self::Other {
-        match dirs.main.axis() {
-            SpecAxis::Horizontal => Gen2::new(self.horizontal, self.vertical),
-            SpecAxis::Vertical => Gen2::new(self.vertical, self.horizontal),
-        }
-    }
-}
-
-/// The two generic layouting axes.
-#[derive(Debug, Copy, Clone, Eq, PartialEq)]
-pub enum GenAxis {
-    /// The axis pages and paragraphs are set along.
-    Main,
-    /// The axis words and lines are set along.
-    Cross,
-}
-
-impl GenAxis {
-    /// The other axis.
-    pub fn other(self) -> Self {
-        match self {
-            Self::Main => Self::Cross,
-            Self::Cross => Self::Main,
-        }
-    }
-}
-
-impl Switch for GenAxis {
-    type Other = SpecAxis;
-
-    fn switch(self, dirs: Gen2<Dir>) -> Self::Other {
-        match self {
-            Self::Main => dirs.main.axis(),
-            Self::Cross => dirs.cross.axis(),
-        }
-    }
-}
-
-impl Display for GenAxis {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.pad(match self {
-            Self::Main => "main",
-            Self::Cross => "cross",
-        })
-    }
-}
-
-/// The two specific layouting axes.
-#[derive(Debug, Copy, Clone, Eq, PartialEq)]
-pub enum SpecAxis {
-    /// The vertical layouting axis.
-    Vertical,
-    /// The horizontal layouting axis.
-    Horizontal,
-}
-
-impl SpecAxis {
-    /// The other axis.
-    pub fn other(self) -> Self {
-        match self {
-            Self::Horizontal => Self::Vertical,
-            Self::Vertical => Self::Horizontal,
-        }
-    }
-}
-
-impl Switch for SpecAxis {
-    type Other = GenAxis;
-
-    fn switch(self, dirs: Gen2<Dir>) -> Self::Other {
-        if self == dirs.main.axis() {
-            GenAxis::Main
-        } else {
-            debug_assert_eq!(self, dirs.cross.axis());
-            GenAxis::Cross
-        }
-    }
-}
-
-impl Display for SpecAxis {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.pad(match self {
-            Self::Vertical => "vertical",
-            Self::Horizontal => "horizontal",
-        })
-    }
-}
-
-/// Where to align content along an axis in a generic context.
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
-pub enum GenAlign {
-    Start,
-    Center,
-    End,
-}
-
-impl GenAlign {
-    /// Returns the position of this alignment in the given length.
-    pub fn apply(self, range: Range<f64>) -> f64 {
-        match self {
-            Self::Start => range.start,
-            Self::Center => (range.start + range.end) / 2.0,
-            Self::End => range.end,
-        }
-    }
-
-    /// The inverse alignment.
-    pub fn inv(self) -> Self {
-        match self {
-            Self::Start => Self::End,
-            Self::Center => Self::Center,
-            Self::End => Self::Start,
-        }
-    }
-}
-
-impl Default for GenAlign {
-    fn default() -> Self {
-        Self::Start
-    }
-}
-
-impl Display for GenAlign {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.pad(match self {
-            Self::Start => "start",
-            Self::Center => "center",
-            Self::End => "end",
-        })
-    }
-}
-
-/// Where to align content along an axis in a specific context.
-#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
-pub enum SpecAlign {
-    Left,
-    Right,
-    Top,
-    Bottom,
-    Center,
-}
-
-impl SpecAlign {
-    /// The specific axis this alignment refers to.
-    ///
-    /// Returns `None` if this is `Center` since the axis is unknown.
-    pub fn axis(self) -> Option<SpecAxis> {
-        match self {
-            Self::Left => Some(SpecAxis::Horizontal),
-            Self::Right => Some(SpecAxis::Horizontal),
-            Self::Top => Some(SpecAxis::Vertical),
-            Self::Bottom => Some(SpecAxis::Vertical),
-            Self::Center => None,
-        }
-    }
-
-    /// The inverse alignment.
-    pub fn inv(self) -> Self {
-        match self {
-            Self::Left => Self::Right,
-            Self::Right => Self::Left,
-            Self::Top => Self::Bottom,
-            Self::Bottom => Self::Top,
-            Self::Center => Self::Center,
-        }
-    }
-}
-
-impl Switch for SpecAlign {
-    type Other = GenAlign;
-
-    fn switch(self, dirs: Gen2<Dir>) -> Self::Other {
-        let get = |dir: Dir, at_positive_start| {
-            if dir.is_positive() == at_positive_start {
-                GenAlign::Start
-            } else {
-                GenAlign::End
-            }
-        };
-
-        let dirs = dirs.switch(dirs);
-        match self {
-            Self::Left => get(dirs.horizontal, true),
-            Self::Right => get(dirs.horizontal, false),
-            Self::Top => get(dirs.vertical, true),
-            Self::Bottom => get(dirs.vertical, false),
-            Self::Center => GenAlign::Center,
-        }
-    }
-}
-
-impl Display for SpecAlign {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.pad(match self {
-            Self::Left => "left",
-            Self::Right => "right",
-            Self::Top => "top",
-            Self::Bottom => "bottom",
-            Self::Center => "center",
-        })
-    }
-}
-
-/// A generic container with left, top, right and bottom components.
-#[derive(Debug, Default, Copy, Clone, Eq, PartialEq)]
-pub struct Sides<T> {
-    /// The value for the left side.
-    pub left: T,
-    /// The value for the top side.
-    pub top: T,
-    /// The value for the right side.
-    pub right: T,
-    /// The value for the bottom side.
-    pub bottom: T,
-}
-
-impl<T> Sides<T> {
-    /// Create a new box from four sizes.
-    pub fn new(left: T, top: T, right: T, bottom: T) -> Self {
-        Self { left, top, right, bottom }
-    }
-
-    /// Create an instance with all four components set to the same `value`.
-    pub fn uniform(value: T) -> Self
-    where
-        T: Clone,
-    {
-        Self {
-            left: value.clone(),
-            top: value.clone(),
-            right: value.clone(),
-            bottom: value,
-        }
-    }
-}
-
-impl Sides<Linear> {
-    /// The absolute insets.
-    pub fn insets(self, Size { width, height }: Size) -> Insets {
-        Insets {
-            x0: -self.left.eval(width),
-            y0: -self.top.eval(height),
-            x1: -self.right.eval(width),
-            y1: -self.bottom.eval(height),
-        }
-    }
-}
-
-impl<T> Get<Side> for Sides<T> {
-    type Component = T;
-
-    fn get(self, side: Side) -> T {
-        match side {
-            Side::Left => self.left,
-            Side::Top => self.top,
-            Side::Right => self.right,
-            Side::Bottom => self.bottom,
-        }
-    }
-
-    fn get_mut(&mut self, side: Side) -> &mut T {
-        match side {
-            Side::Left => &mut self.left,
-            Side::Top => &mut self.top,
-            Side::Right => &mut self.right,
-            Side::Bottom => &mut self.bottom,
-        }
-    }
-}
-
-/// A side of a container.
-#[derive(Debug, Copy, Clone, Eq, PartialEq)]
-pub enum Side {
-    Left,
-    Top,
-    Right,
-    Bottom,
-}
-
-impl Side {
-    /// The opposite side.
-    pub fn inv(self) -> Self {
-        match self {
-            Self::Left => Self::Right,
-            Self::Top => Self::Bottom,
-            Self::Right => Self::Left,
-            Self::Bottom => Self::Top,
-        }
-    }
-}
diff --git a/src/layout/nodes/spacing.rs b/src/layout/spacing.rs
index 9d72f7ca..9eac1ad5 100644
--- a/src/layout/nodes/spacing.rs
+++ b/src/layout/spacing.rs
@@ -5,7 +5,7 @@ use super::*;
 /// A node that inserts spacing.
 #[derive(Copy, Clone, PartialEq)]
 pub struct Spacing {
-    pub amount: f64,
+    pub amount: Length,
     pub softness: Softness,
 }
 
diff --git a/src/layout/nodes/stack.rs b/src/layout/stack.rs
index cca64e62..6cbe03e3 100644
--- a/src/layout/nodes/stack.rs
+++ b/src/layout/stack.rs
@@ -24,10 +24,10 @@ use super::*;
 /// sentence in the second box.
 #[derive(Debug, Clone, PartialEq)]
 pub struct Stack {
-    pub dirs: Gen2<Dir>,
+    pub dirs: Gen<Dir>,
     pub children: Vec<LayoutNode>,
-    pub aligns: Gen2<GenAlign>,
-    pub expand: Spec2<bool>,
+    pub aligns: Gen<Align>,
+    pub expand: Spec<bool>,
 }
 
 #[async_trait(?Send)]
@@ -90,17 +90,17 @@ impl Layout for Stack {
 }
 
 struct StackSpace {
-    dirs: Gen2<Dir>,
-    expand: Spec2<bool>,
-    boxes: Vec<(BoxLayout, Gen2<GenAlign>)>,
+    dirs: Gen<Dir>,
+    expand: Spec<bool>,
+    boxes: Vec<(BoxLayout, Gen<Align>)>,
     full_size: Size,
     usable: Size,
     used: Size,
-    ruler: GenAlign,
+    ruler: Align,
 }
 
 impl StackSpace {
-    fn new(dirs: Gen2<Dir>, expand: Spec2<bool>, size: Size) -> Self {
+    fn new(dirs: Gen<Dir>, expand: Spec<bool>, size: Size) -> Self {
         Self {
             dirs,
             expand,
@@ -108,14 +108,14 @@ impl StackSpace {
             full_size: size,
             usable: size,
             used: Size::ZERO,
-            ruler: GenAlign::Start,
+            ruler: Align::Start,
         }
     }
 
     fn push_box(
         &mut self,
         boxed: BoxLayout,
-        aligns: Gen2<GenAlign>,
+        aligns: Gen<Align>,
     ) -> Result<(), BoxLayout> {
         let main = self.dirs.main.axis();
         let cross = self.dirs.cross.axis();
@@ -133,15 +133,15 @@ impl StackSpace {
         Ok(())
     }
 
-    fn push_spacing(&mut self, spacing: f64) {
+    fn push_spacing(&mut self, spacing: Length) {
         let main = self.dirs.main.axis();
         let max = self.usable.get(main);
         let trimmed = spacing.min(max);
         *self.used.get_mut(main) += trimmed;
         *self.usable.get_mut(main) -= trimmed;
 
-        let size = Gen2::new(trimmed, 0.0).switch(self.dirs);
-        self.boxes.push((BoxLayout::new(size.to_size()), Gen2::default()));
+        let size = Gen::new(trimmed, Length::ZERO).switch(self.dirs);
+        self.boxes.push((BoxLayout::new(size.to_size()), Gen::default()));
     }
 
     fn finish(mut self) -> BoxLayout {
@@ -156,7 +156,7 @@ impl StackSpace {
             self.used.height = self.full_size.height;
         }
 
-        let mut sum = 0.0;
+        let mut sum = Length::ZERO;
         let mut sums = Vec::with_capacity(self.boxes.len() + 1);
 
         for (boxed, _) in &self.boxes {
@@ -183,14 +183,14 @@ impl StackSpace {
 
             let cross_len = used.cross - size.cross;
             let cross_range = if dirs.cross.is_positive() {
-                0.0 .. cross_len
+                Length::ZERO .. cross_len
             } else {
-                cross_len .. 0.0
+                cross_len .. Length::ZERO
             };
 
             let main = aligns.main.apply(main_range);
             let cross = aligns.cross.apply(cross_range);
-            let pos = Gen2::new(main, cross).switch(dirs).to_point();
+            let pos = Gen::new(main, cross).switch(dirs).to_point();
 
             layout.push_layout(pos, boxed);
         }
diff --git a/src/layout/nodes/text.rs b/src/layout/text.rs
index b0c4a458..fafc1b14 100644
--- a/src/layout/nodes/text.rs
+++ b/src/layout/text.rs
@@ -10,11 +10,11 @@ use crate::shaping;
 #[derive(Clone, PartialEq)]
 pub struct Text {
     pub text: String,
-    pub size: f64,
+    pub size: Length,
     pub dir: Dir,
     pub fallback: Rc<FallbackTree>,
     pub variant: FontVariant,
-    pub aligns: Gen2<GenAlign>,
+    pub aligns: Gen<Align>,
 }
 
 #[async_trait(?Send)]
diff --git a/src/length.rs b/src/length.rs
deleted file mode 100644
index 437c741d..00000000
--- a/src/length.rs
+++ /dev/null
@@ -1,203 +0,0 @@
-//! A length type with a unit.
-
-use std::fmt::{self, Debug, Display, Formatter};
-use std::str::FromStr;
-
-/// A length with a unit.
-#[derive(Copy, Clone, PartialEq)]
-pub struct Length {
-    /// The length in the given unit.
-    pub val: f64,
-    /// The unit of measurement.
-    pub unit: Unit,
-}
-
-/// Different units of measurement.
-#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
-pub enum Unit {
-    /// Points.
-    Pt,
-    /// Millimeters.
-    Mm,
-    /// Centimeters.
-    Cm,
-    /// Inches.
-    In,
-    /// Raw units (the implicit unit of all bare `f64` lengths).
-    Raw,
-}
-
-impl Length {
-    /// Create a length from a value with a unit.
-    pub const fn new(val: f64, unit: Unit) -> Self {
-        Self { val, unit }
-    }
-
-    /// Create a length from a number of points.
-    pub const fn pt(pt: f64) -> Self {
-        Self::new(pt, Unit::Pt)
-    }
-
-    /// Create a length from a number of millimeters.
-    pub const fn mm(mm: f64) -> Self {
-        Self::new(mm, Unit::Mm)
-    }
-
-    /// Create a length from a number of centimeters.
-    pub const fn cm(cm: f64) -> Self {
-        Self::new(cm, Unit::Cm)
-    }
-
-    /// Create a length from a number of inches.
-    pub const fn inches(inches: f64) -> Self {
-        Self::new(inches, Unit::In)
-    }
-
-    /// Create a length from a number of raw units.
-    pub const fn raw(raw: f64) -> Self {
-        Self::new(raw, Unit::Raw)
-    }
-
-    /// Convert this to a number of points.
-    pub fn as_pt(self) -> f64 {
-        self.with_unit(Unit::Pt).val
-    }
-
-    /// Convert this to a number of millimeters.
-    pub fn as_mm(self) -> f64 {
-        self.with_unit(Unit::Mm).val
-    }
-
-    /// Convert this to a number of centimeters.
-    pub fn as_cm(self) -> f64 {
-        self.with_unit(Unit::Cm).val
-    }
-
-    /// Convert this to a number of inches.
-    pub fn as_inches(self) -> f64 {
-        self.with_unit(Unit::In).val
-    }
-
-    /// Get the value of this length in raw units.
-    pub fn as_raw(self) -> f64 {
-        self.with_unit(Unit::Raw).val
-    }
-
-    /// Convert this to a length with a different unit.
-    pub fn with_unit(self, unit: Unit) -> Self {
-        Self {
-            val: self.val * self.unit.raw_scale() / unit.raw_scale(),
-            unit,
-        }
-    }
-}
-
-impl Unit {
-    /// How many raw units correspond to a value of `1.0` in this unit.
-    fn raw_scale(self) -> f64 {
-        match self {
-            Unit::Pt => 1.0,
-            Unit::Mm => 2.83465,
-            Unit::Cm => 28.3465,
-            Unit::In => 72.0,
-            Unit::Raw => 1.0,
-        }
-    }
-}
-
-impl Display for Length {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        write!(f, "{:.2}{}", self.val, self.unit)
-    }
-}
-
-impl Debug for Length {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        Display::fmt(self, f)
-    }
-}
-
-impl Display for Unit {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.pad(match self {
-            Unit::Mm => "mm",
-            Unit::Pt => "pt",
-            Unit::Cm => "cm",
-            Unit::In => "in",
-            Unit::Raw => "rw",
-        })
-    }
-}
-
-impl Debug for Unit {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        Display::fmt(self, f)
-    }
-}
-
-impl FromStr for Length {
-    type Err = ParseLengthError;
-
-    fn from_str(src: &str) -> Result<Self, Self::Err> {
-        let len = src.len();
-
-        // We need at least some number and the unit.
-        if len <= 2 {
-            return Err(ParseLengthError);
-        }
-
-        // We can view the string as bytes since a multibyte UTF-8 char cannot
-        // have valid ASCII chars as subbytes.
-        let split = len - 2;
-        let bytes = src.as_bytes();
-        let unit = match &bytes[split ..] {
-            b"pt" => Unit::Pt,
-            b"mm" => Unit::Mm,
-            b"cm" => Unit::Cm,
-            b"in" => Unit::In,
-            _ => return Err(ParseLengthError),
-        };
-
-        src[.. split]
-            .parse::<f64>()
-            .map(|val| Self::new(val, unit))
-            .map_err(|_| ParseLengthError)
-    }
-}
-
-/// The error when parsing a length fails.
-#[derive(Debug, Copy, Clone, Eq, PartialEq)]
-pub struct ParseLengthError;
-
-impl std::error::Error for ParseLengthError {}
-
-impl Display for ParseLengthError {
-    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
-        f.pad("invalid string for length")
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn test_length_from_str_parses_correct_value_and_unit() {
-        assert_eq!(Length::from_str("2.5cm"), Ok(Length::cm(2.5)));
-    }
-
-    #[test]
-    fn test_length_from_str_works_with_non_ascii_chars() {
-        assert_eq!(Length::from_str("123🚚"), Err(ParseLengthError));
-    }
-
-    #[test]
-    fn test_length_formats_correctly() {
-        assert_eq!(Length::cm(12.728).to_string(), "12.73cm".to_string());
-    }
-
-    #[test]
-    fn test_length_unit_conversion() {
-        assert!((Length::mm(150.0).as_cm() - 15.0) < 1e-4);
-    }
-}
diff --git a/src/lib.rs b/src/lib.rs
index 22e3b988..381270c9 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -30,13 +30,13 @@
 
 #[macro_use]
 pub mod diag;
-pub mod color;
+#[macro_use]
 pub mod eval;
+pub mod color;
 pub mod export;
 pub mod font;
 pub mod geom;
 pub mod layout;
-pub mod length;
 pub mod library;
 pub mod paper;
 pub mod parse;
diff --git a/src/library/align.rs b/src/library/align.rs
index acd3a85c..d6b14692 100644
--- a/src/library/align.rs
+++ b/src/library/align.rs
@@ -1,4 +1,5 @@
 use crate::prelude::*;
+use std::fmt::{self, Display, Formatter};
 
 /// `align`: Align content along the layouting axes.
 ///
@@ -18,10 +19,10 @@ pub fn align(mut args: Args, ctx: &mut EvalContext) -> Value {
     let snapshot = ctx.state.clone();
 
     let body = args.find::<SynTree>();
-    let first = args.get::<_, Spanned<SpecAlign>>(ctx, 0);
-    let second = args.get::<_, Spanned<SpecAlign>>(ctx, 1);
-    let hor = args.get::<_, Spanned<SpecAlign>>(ctx, "horizontal");
-    let ver = args.get::<_, Spanned<SpecAlign>>(ctx, "vertical");
+    let first = args.get::<_, Spanned<AlignArg>>(ctx, 0);
+    let second = args.get::<_, Spanned<AlignArg>>(ctx, 1);
+    let hor = args.get::<_, Spanned<AlignArg>>(ctx, "horizontal");
+    let ver = args.get::<_, Spanned<AlignArg>>(ctx, "vertical");
     args.done(ctx);
 
     let iter = first
@@ -50,10 +51,10 @@ pub fn align(mut args: Args, ctx: &mut EvalContext) -> Value {
 /// Deduplicate alignments and deduce to which axes they apply.
 fn dedup_aligns(
     ctx: &mut EvalContext,
-    iter: impl Iterator<Item = (Option<SpecAxis>, Spanned<SpecAlign>)>,
-) -> Gen2<GenAlign> {
+    iter: impl Iterator<Item = (Option<SpecAxis>, Spanned<AlignArg>)>,
+) -> Gen<Align> {
     let mut aligns = ctx.state.aligns;
-    let mut had = Gen2::new(false, false);
+    let mut had = Gen::new(false, false);
     let mut had_center = false;
 
     for (axis, Spanned { v: align, span }) in iter {
@@ -77,15 +78,15 @@ fn dedup_aligns(
         } else {
             // We don't know the axis: This has to be a `center` alignment for a
             // positional argument.
-            debug_assert_eq!(align, SpecAlign::Center);
+            debug_assert_eq!(align, AlignArg::Center);
 
             if had.main && had.cross {
                 ctx.diag(error!(span, "duplicate alignment"));
             } else if had_center {
                 // Both this and the previous one are unspecified `center`
                 // alignments. Both axes should be centered.
-                aligns = Gen2::new(GenAlign::Center, GenAlign::Center);
-                had = Gen2::new(true, true);
+                aligns = Gen::new(Align::Center, Align::Center);
+                had = Gen::new(true, true);
             } else {
                 had_center = true;
             }
@@ -95,10 +96,10 @@ fn dedup_aligns(
         // alignment.
         if had_center && (had.main || had.cross) {
             if had.main {
-                aligns.cross = GenAlign::Center;
+                aligns.cross = Align::Center;
                 had.cross = true;
             } else {
-                aligns.main = GenAlign::Center;
+                aligns.main = Align::Center;
                 had.main = true;
             }
             had_center = false;
@@ -108,8 +109,77 @@ fn dedup_aligns(
     // If center has not been flushed by now, it is the only argument and then
     // we default to applying it to the cross axis.
     if had_center {
-        aligns.cross = GenAlign::Center;
+        aligns.cross = Align::Center;
     }
 
     aligns
 }
+
+/// An alignment argument.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd)]
+enum AlignArg {
+    Left,
+    Right,
+    Top,
+    Bottom,
+    Center,
+}
+
+impl AlignArg {
+    /// The specific axis this alignment refers to.
+    ///
+    /// Returns `None` if this is `Center` since the axis is unknown.
+    pub fn axis(self) -> Option<SpecAxis> {
+        match self {
+            Self::Left => Some(SpecAxis::Horizontal),
+            Self::Right => Some(SpecAxis::Horizontal),
+            Self::Top => Some(SpecAxis::Vertical),
+            Self::Bottom => Some(SpecAxis::Vertical),
+            Self::Center => None,
+        }
+    }
+}
+
+impl Switch for AlignArg {
+    type Other = Align;
+
+    fn switch(self, dirs: Gen<Dir>) -> Self::Other {
+        let get = |dir: Dir, at_positive_start| {
+            if dir.is_positive() == at_positive_start {
+                Align::Start
+            } else {
+                Align::End
+            }
+        };
+
+        let dirs = dirs.switch(dirs);
+        match self {
+            Self::Left => get(dirs.horizontal, true),
+            Self::Right => get(dirs.horizontal, false),
+            Self::Top => get(dirs.vertical, true),
+            Self::Bottom => get(dirs.vertical, false),
+            Self::Center => Align::Center,
+        }
+    }
+}
+
+convert_ident!(AlignArg, "alignment", |v| match v {
+    "left" => Some(Self::Left),
+    "right" => Some(Self::Right),
+    "top" => Some(Self::Top),
+    "bottom" => Some(Self::Bottom),
+    "center" => Some(Self::Center),
+    _ => None,
+});
+
+impl Display for AlignArg {
+    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
+        f.pad(match self {
+            Self::Left => "left",
+            Self::Right => "right",
+            Self::Top => "top",
+            Self::Bottom => "bottom",
+            Self::Center => "center",
+        })
+    }
+}
diff --git a/src/library/boxed.rs b/src/library/boxed.rs
index 6edb3b17..0c1ed30a 100644
--- a/src/library/boxed.rs
+++ b/src/library/boxed.rs
@@ -1,5 +1,5 @@
 use crate::geom::Linear;
-use crate::layout::nodes::{Fixed, Stack};
+use crate::layout::{Fixed, Stack};
 use crate::prelude::*;
 
 /// `box`: Layouts its contents into a box.
@@ -33,7 +33,7 @@ pub fn boxed(mut args: Args, ctx: &mut EvalContext) -> Value {
             dirs,
             children,
             aligns,
-            expand: Spec2::new(width.is_some(), height.is_some()),
+            expand: Spec::new(width.is_some(), height.is_some()),
         }),
     });
 
diff --git a/src/library/font.rs b/src/library/font.rs
index be6823c3..e6d9cd12 100644
--- a/src/library/font.rs
+++ b/src/library/font.rs
@@ -57,9 +57,9 @@ pub fn font(mut args: Args, ctx: &mut EvalContext) -> Value {
     let body = args.find::<SynTree>();
 
     if let Some(linear) = args.find::<Linear>() {
-        if linear.rel == 0.0 {
+        if linear.is_absolute() {
             ctx.state.text.font_size.base = linear.abs;
-            ctx.state.text.font_size.scale = Linear::rel(1.0);
+            ctx.state.text.font_size.scale = Relative::ONE.into();
         } else {
             ctx.state.text.font_size.scale = linear;
         }
diff --git a/src/library/page.rs b/src/library/page.rs
index 3c6703bc..570dbb10 100644
--- a/src/library/page.rs
+++ b/src/library/page.rs
@@ -1,7 +1,6 @@
 use std::mem;
 
-use crate::eval::Absolute;
-use crate::geom::Linear;
+use crate::geom::{Length, Linear};
 use crate::paper::{Paper, PaperClass};
 use crate::prelude::*;
 
@@ -25,12 +24,12 @@ pub fn page(mut args: Args, ctx: &mut EvalContext) -> Value {
         ctx.state.page.size = paper.size();
     }
 
-    if let Some(Absolute(width)) = args.get::<_, Absolute>(ctx, "width") {
+    if let Some(width) = args.get::<_, Length>(ctx, "width") {
         ctx.state.page.class = PaperClass::Custom;
         ctx.state.page.size.width = width;
     }
 
-    if let Some(Absolute(height)) = args.get::<_, Absolute>(ctx, "height") {
+    if let Some(height) = args.get::<_, Length>(ctx, "height") {
         ctx.state.page.class = PaperClass::Custom;
         ctx.state.page.size.height = height;
     }
diff --git a/src/library/spacing.rs b/src/library/spacing.rs
index 6d00bd1c..a2b21e93 100644
--- a/src/library/spacing.rs
+++ b/src/library/spacing.rs
@@ -1,5 +1,5 @@
 use crate::geom::Linear;
-use crate::layout::nodes::{Softness, Spacing};
+use crate::layout::{Softness, Spacing};
 use crate::prelude::*;
 
 /// `h`: Add horizontal spacing.
diff --git a/src/paper.rs b/src/paper.rs
index 21762b17..21f54756 100644
--- a/src/paper.rs
+++ b/src/paper.rs
@@ -1,18 +1,16 @@
 //! Predefined papers.
 
-use crate::geom::{Linear, Size};
-use crate::layout::Sides;
-use crate::length::Length;
+use crate::geom::{Length, Linear, Relative, Sides, Size};
 
 /// Specification of a paper.
 #[derive(Debug, Copy, Clone, PartialEq)]
 pub struct Paper {
     /// The kind of paper, which defines the default margins.
     pub class: PaperClass,
-    /// The width of the paper.
-    pub width: Length,
-    /// The height of the paper.
-    pub height: Length,
+    /// The width of the paper in millimeters.
+    pub width: f64,
+    /// The height of the paper in millimeters.
+    pub height: f64,
 }
 
 impl Paper {
@@ -23,7 +21,7 @@ impl Paper {
 
     /// The size of the paper.
     pub fn size(self) -> Size {
-        Size::new(self.width.as_raw(), self.height.as_raw())
+        Size::new(Length::mm(self.width), Length::mm(self.height))
     }
 }
 
@@ -40,7 +38,7 @@ pub enum PaperClass {
 impl PaperClass {
     /// The default margins for this page class.
     pub fn default_margins(self) -> Sides<Linear> {
-        let f = Linear::rel;
+        let f = |r| Relative::new(r).into();
         let s = |l, r, t, b| Sides::new(f(l), f(r), f(t), f(b));
         match self {
             Self::Custom => s(0.1190, 0.0842, 0.1190, 0.0842),
@@ -69,9 +67,9 @@ macro_rules! papers {
         #[doc = $names]
         #[doc = "`."]
         pub const $var: Paper = Paper {
-            width: Length::mm($width),
-            height: Length::mm($height),
             class: PaperClass::$class,
+            width: $width,
+            height: $height,
         };
     };
 }
diff --git a/src/parse/mod.rs b/src/parse/mod.rs
index 3d980d7c..90fdbf5d 100644
--- a/src/parse/mod.rs
+++ b/src/parse/mod.rs
@@ -432,7 +432,7 @@ fn value(p: &mut Parser) -> Option<Expr> {
         Token::Bool(b) => Expr::Lit(Lit::Bool(b)),
         Token::Int(i) => Expr::Lit(Lit::Int(i)),
         Token::Float(f) => Expr::Lit(Lit::Float(f)),
-        Token::Length(l) => Expr::Lit(Lit::Length(l)),
+        Token::Length(val, unit) => Expr::Lit(Lit::Length(val, unit)),
         Token::Percent(p) => Expr::Lit(Lit::Percent(p)),
         Token::Hex(hex) => Expr::Lit(Lit::Color(color(p, hex, start))),
         Token::Str(token) => Expr::Lit(Lit::Str(string(p, token))),
diff --git a/src/parse/tests.rs b/src/parse/tests.rs
index d76c6dca..e0712b36 100644
--- a/src/parse/tests.rs
+++ b/src/parse/tests.rs
@@ -8,7 +8,7 @@ use super::parse;
 use crate::color::RgbaColor;
 use crate::diag::Deco;
 use crate::eval::DictKey;
-use crate::length::Length;
+use crate::geom::Unit;
 use crate::syntax::*;
 
 // ------------------------------ Construct Syntax Nodes ------------------------------ //
@@ -51,6 +51,7 @@ macro_rules! F {
 
 use BinOp::*;
 use UnOp::*;
+use Unit::*;
 
 fn Id(ident: &str) -> Expr {
     Expr::Lit(Lit::Ident(Ident(ident.to_string())))
@@ -67,8 +68,8 @@ fn Float(float: f64) -> Expr {
 fn Percent(percent: f64) -> Expr {
     Expr::Lit(Lit::Percent(percent))
 }
-fn Len(length: Length) -> Expr {
-    Expr::Lit(Lit::Length(length))
+fn Length(val: f64, unit: Unit) -> Expr {
+    Expr::Lit(Lit::Length(val, unit))
 }
 fn Color(color: RgbaColor) -> Expr {
     Expr::Lit(Lit::Color(color))
@@ -347,10 +348,10 @@ fn test_parse_chaining() {
     // Things the parser has to make sense of
     t!("[hi: (5.0, 2.1 >> you]" => F!("hi"; Dict![Float(5.0), Float(2.1)], Tree![F!("you")]));
     t!("[box >> pad: 1pt][Hi]"  => F!("box"; Tree![
-        F!("pad"; Len(Length::pt(1.0)), Tree!(T("Hi")))
+        F!("pad"; Length(1.0, Pt), Tree!(T("Hi")))
     ]));
     t!("[bold: 400, >> emph >> sub: 1cm]" => F!("bold"; Int(400), Tree![
-        F!("emph"; Tree!(F!("sub"; Len(Length::cm(1.0)))))
+        F!("emph"; Tree!(F!("sub"; Length(1.0, Cm))))
     ]));
 
     // Errors for unclosed / empty predecessor groups
@@ -411,8 +412,8 @@ fn test_parse_values() {
     v!("1.0e-4"    => Float(1e-4));
     v!("3.15"      => Float(3.15));
     v!("50%"       => Percent(50.0));
-    v!("4.5cm"     => Len(Length::cm(4.5)));
-    v!("12e1pt"    => Len(Length::pt(12e1)));
+    v!("4.5cm"     => Length(4.5, Cm));
+    v!("12e1pt"    => Length(12e1, Pt));
     v!("#f7a20500" => Color(RgbaColor::new(0xf7, 0xa2, 0x05, 0x00)));
     v!("\"a\n[]\\\"string\"" => Str("a\n[]\"string"));
 
@@ -446,15 +447,15 @@ fn test_parse_expressions() {
     // Operations.
     v!("-1"          => Unary(Neg, Int(1)));
     v!("-- 1"        => Unary(Neg, Unary(Neg, Int(1))));
-    v!("3.2in + 6pt" => Binary(Add, Len(Length::inches(3.2)), Len(Length::pt(6.0))));
+    v!("3.2in + 6pt" => Binary(Add, Length(3.2, In), Length(6.0, Pt)));
     v!("5 - 0.01"    => Binary(Sub, Int(5), Float(0.01)));
-    v!("(3mm * 2)"   => Binary(Mul, Len(Length::mm(3.0)), Int(2)));
-    v!("12e-3cm/1pt" => Binary(Div, Len(Length::cm(12e-3)), Len(Length::pt(1.0))));
+    v!("(3mm * 2)"   => Binary(Mul, Length(3.0, Mm), Int(2)));
+    v!("12e-3cm/1pt" => Binary(Div, Length(12e-3, Cm), Length(1.0, Pt)));
 
     // More complex.
     v!("(3.2in + 6pt)*(5/2-1)" => Binary(
         Mul,
-        Binary(Add, Len(Length::inches(3.2)), Len(Length::pt(6.0))),
+        Binary(Add, Length(3.2, In), Length(6.0, Pt)),
         Binary(Sub, Binary(Div, Int(5), Int(2)), Int(1))
     ));
     v!("(6.3E+2+4* - 3.2pt)/2" => Binary(
@@ -462,7 +463,7 @@ fn test_parse_expressions() {
         Binary(Add, Float(6.3e2), Binary(
             Mul,
             Int(4),
-            Unary(Neg, Len(Length::pt(3.2)))
+            Unary(Neg, Length(3.2, Pt))
         )),
         Int(2)
     ));
@@ -483,11 +484,11 @@ fn test_parse_expressions() {
     ts!("[val: (1)]" => s(0, 10, F!(s(1, 4, "val"), 5 .. 9; s(6, 9, Int(1)))));
 
     // Invalid expressions.
-    v!("4pt--"        => Len(Length::pt(4.0)));
+    v!("4pt--"        => Length(4.0, Pt));
     e!("[val: 4pt--]" => s(10, 11, "missing factor"),
                          s(6, 10, "missing right summand"));
 
-    v!("3mm+4pt*"        => Binary(Add, Len(Length::mm(3.0)), Len(Length::pt(4.0))));
+    v!("3mm+4pt*"        => Binary(Add, Length(3.0, Mm), Length(4.0, Pt)));
     e!("[val: 3mm+4pt*]" => s(10, 14, "missing right factor"));
 }
 
@@ -525,7 +526,7 @@ fn test_parse_dicts_compute_func_calls() {
     // More complex.
     v!("css(1pt, rgb(90, 102, 254), \"solid\")" => Call!(
         "css";
-        Len(Length::pt(1.0)),
+        Length(1.0, Pt),
         Call!("rgb"; Int(90), Int(102), Int(254)),
         Str("solid"),
     ));
@@ -546,7 +547,7 @@ fn test_parse_dicts_nested() {
             Int(1),
             Dict!(
                 "ab" => Dict![],
-                "d"  => Dict!(Int(3), Len(Length::pt(14.0))),
+                "d"  => Dict!(Int(3), Length(14.0, Pt)),
             ),
         ],
         Bool(false),
diff --git a/src/parse/tokens.rs b/src/parse/tokens.rs
index 2ff580b6..f53ab586 100644
--- a/src/parse/tokens.rs
+++ b/src/parse/tokens.rs
@@ -3,7 +3,7 @@
 use std::fmt::{self, Debug, Formatter};
 
 use super::{is_newline, Scanner};
-use crate::length::Length;
+use crate::geom::Unit;
 use crate::syntax::token::*;
 use crate::syntax::{is_ident, Pos};
 
@@ -279,8 +279,8 @@ fn parse_expr(text: &str) -> Token<'_> {
         Token::Float(num)
     } else if let Some(percent) = parse_percent(text) {
         Token::Percent(percent)
-    } else if let Ok(length) = text.parse::<Length>() {
-        Token::Length(length)
+    } else if let Some((val, unit)) = parse_length(text) {
+        Token::Length(val, unit)
     } else if is_ident(text) {
         Token::Ident(text)
     } else {
@@ -292,19 +292,41 @@ fn parse_percent(text: &str) -> Option<f64> {
     text.strip_suffix('%').and_then(|num| num.parse::<f64>().ok())
 }
 
+fn parse_length(text: &str) -> Option<(f64, Unit)> {
+    let len = text.len();
+
+    // We need at least some number and the unit.
+    if len <= 2 {
+        return None;
+    }
+
+    // We can view the string as bytes since a multibyte UTF-8 char cannot
+    // have valid ASCII chars as subbytes.
+    let split = len - 2;
+    let bytes = text.as_bytes();
+    let unit = match &bytes[split ..] {
+        b"pt" => Unit::Pt,
+        b"mm" => Unit::Mm,
+        b"cm" => Unit::Cm,
+        b"in" => Unit::In,
+        _ => return None,
+    };
+
+    text[.. split].parse::<f64>().ok().map(|val| (val, unit))
+}
+
 #[cfg(test)]
 #[allow(non_snake_case)]
 mod tests {
     use super::*;
-    use crate::length::Length;
     use crate::parse::tests::check;
 
     use Token::{
-        BlockComment as BC, Bool, Chain, Float, Hex, Hyphen as Min, Ident as Id, Int,
-        LeftBrace as LB, LeftBracket as L, LeftParen as LP, Length as Len,
-        LineComment as LC, NonBreakingSpace as Nbsp, Percent, Plus, RightBrace as RB,
-        RightBracket as R, RightParen as RP, Slash, Space as S, Star, Text as T, *,
+        BlockComment as BC, Hyphen as Min, Ident as Id, LeftBrace as LB,
+        LeftBracket as L, LeftParen as LP, LineComment as LC, NonBreakingSpace as Nbsp,
+        RightBrace as RB, RightBracket as R, RightParen as RP, Space as S, Text as T, *,
     };
+    use Unit::*;
 
     fn Str(string: &str, terminated: bool) -> Token {
         Token::Str(TokenStr { string, terminated })
@@ -325,6 +347,16 @@ mod tests {
     }
 
     #[test]
+    fn test_length_from_str_parses_correct_value_and_unit() {
+        assert_eq!(parse_length("2.5cm"), Some((2.5, Cm)));
+    }
+
+    #[test]
+    fn test_length_from_str_works_with_non_ascii_chars() {
+        assert_eq!(parse_length("123🚚"), None);
+    }
+
+    #[test]
     fn tokenize_whitespace() {
         t!(Body, ""             => );
         t!(Body, " "            => S(0));
@@ -429,7 +461,7 @@ mod tests {
         t!(Header, "🌓, 🌍,"     => Invalid("🌓"), Comma, S(0), Invalid("🌍"), Comma);
         t!(Header, "{abc}"        => LB, Id("abc"), RB);
         t!(Header, "(1,2)"        => LP, Int(1), Comma, Int(2), RP);
-        t!(Header, "12_pt, 12pt"  => Invalid("12_pt"), Comma, S(0), Len(Length::pt(12.0)));
+        t!(Header, "12_pt, 12pt"  => Invalid("12_pt"), Comma, S(0), Length(12.0, Pt));
         t!(Header, "f: arg >> g"  => Id("f"), Colon, S(0), Id("arg"), S(0), Chain, S(0), Id("g"));
         t!(Header, "=3.15"        => Equals, Float(3.15));
         t!(Header, "arg, _b, _1"  => Id("arg"), Comma, S(0), Id("_b"), Comma, S(0), Id("_1"));
@@ -446,9 +478,9 @@ mod tests {
         t!(Header, "12.3e5"  => Float(12.3e5));
         t!(Header, "120%"    => Percent(120.0));
         t!(Header, "12e4%"   => Percent(120000.0));
-        t!(Header, "1e5in"   => Len(Length::inches(100000.0)));
-        t!(Header, "2.3cm"   => Len(Length::cm(2.3)));
-        t!(Header, "02.4mm"  => Len(Length::mm(2.4)));
+        t!(Header, "1e5in"   => Length(100000.0, In));
+        t!(Header, "2.3cm"   => Length(2.3, Cm));
+        t!(Header, "02.4mm"  => Length(2.4, Mm));
         t!(Header, "2.4.cm"  => Invalid("2.4.cm"));
         t!(Header, "#6ae6dd" => Hex("6ae6dd"));
         t!(Header, "#8A083c" => Hex("8A083c"));
@@ -469,11 +501,11 @@ mod tests {
 
     #[test]
     fn tokenize_math() {
-        t!(Header, "12e-3in"           => Len(Length::inches(12e-3)));
+        t!(Header, "12e-3in"           => Length(12e-3, In));
         t!(Header, "-1"                => Min, Int(1));
         t!(Header, "--1"               => Min, Min, Int(1));
         t!(Header, "- 1"               => Min, S(0), Int(1));
-        t!(Header, "6.1cm + 4pt,a=1*2" => Len(Length::cm(6.1)), S(0), Plus, S(0), Len(Length::pt(4.0)),
+        t!(Header, "6.1cm + 4pt,a=1*2" => Length(6.1, Cm), S(0), Plus, S(0), Length(4.0, Pt),
                                           Comma, Id("a"), Equals, Int(1), Star, Int(2));
         t!(Header, "(5 - 1) / 2.1"     => LP, Int(5), S(0), Min, S(0), Int(1), RP,
                                           S(0), Slash, S(0), Float(2.1));
diff --git a/src/prelude.rs b/src/prelude.rs
index 82da91f4..16b598ce 100644
--- a/src/prelude.rs
+++ b/src/prelude.rs
@@ -3,8 +3,9 @@
 pub use crate::diag::{Feedback, Pass};
 #[doc(no_inline)]
 pub use crate::eval::{Args, Dict, Eval, EvalContext, Value, ValueDict};
-pub use crate::layout::nodes::LayoutNode;
-pub use crate::layout::primitive::*;
+pub use crate::geom::*;
+#[doc(no_inline)]
+pub use crate::layout::LayoutNode;
 #[doc(no_inline)]
 pub use crate::syntax::{Span, Spanned, SynTree};
 pub use crate::{error, warning};
diff --git a/src/shaping.rs b/src/shaping.rs
index c620f872..bc6fb6b7 100644
--- a/src/shaping.rs
+++ b/src/shaping.rs
@@ -10,8 +10,8 @@ use fontdock::{FaceId, FaceQuery, FallbackTree, FontVariant};
 use ttf_parser::{Face, GlyphId};
 
 use crate::font::FontLoader;
-use crate::geom::{Point, Size};
-use crate::layout::{BoxLayout, Dir, LayoutElement};
+use crate::geom::{Dir, Length, Point, Size};
+use crate::layout::{BoxLayout, LayoutElement};
 
 /// A shaped run of text.
 #[derive(Clone, PartialEq)]
@@ -24,14 +24,14 @@ pub struct Shaped {
     pub glyphs: Vec<GlyphId>,
     /// The horizontal offsets of the glyphs. This is indexed parallel to `glyphs`.
     /// Vertical offets are not yet supported.
-    pub offsets: Vec<f64>,
+    pub offsets: Vec<Length>,
     /// The font size.
-    pub size: f64,
+    pub size: Length,
 }
 
 impl Shaped {
     /// Create a new shape run with empty `text`, `glyphs` and `offsets`.
-    pub fn new(face: FaceId, size: f64) -> Self {
+    pub fn new(face: FaceId, size: Length) -> Self {
         Self {
             text: String::new(),
             face,
@@ -63,15 +63,15 @@ impl Debug for Shaped {
 /// [`Shaped`]: struct.Shaped.html
 pub async fn shape(
     text: &str,
-    size: f64,
+    size: Length,
     dir: Dir,
     loader: &mut FontLoader,
     fallback: &FallbackTree,
     variant: FontVariant,
 ) -> BoxLayout {
-    let mut layout = BoxLayout::new(Size::new(0.0, size));
+    let mut layout = BoxLayout::new(Size::new(Length::ZERO, size));
     let mut shaped = Shaped::new(FaceId::MAX, size);
-    let mut offset = 0.0;
+    let mut offset = Length::ZERO;
 
     // Create an iterator with conditional direction.
     let mut forwards = text.chars();
@@ -93,11 +93,11 @@ pub async fn shape(
 
             // Flush the buffer if we change the font face.
             if shaped.face != id && !shaped.text.is_empty() {
-                let pos = Point::new(layout.size.width, 0.0);
+                let pos = Point::new(layout.size.width, Length::ZERO);
                 layout.push(pos, LayoutElement::Text(shaped));
                 layout.size.width += offset;
                 shaped = Shaped::new(FaceId::MAX, size);
-                offset = 0.0;
+                offset = Length::ZERO;
             }
 
             shaped.face = id;
@@ -110,7 +110,7 @@ pub async fn shape(
 
     // Flush the last buffered parts of the word.
     if !shaped.text.is_empty() {
-        let pos = Point::new(layout.size.width, 0.0);
+        let pos = Point::new(layout.size.width, Length::ZERO);
         layout.push(pos, LayoutElement::Text(shaped));
         layout.size.width += offset;
     }
@@ -120,7 +120,7 @@ pub async fn shape(
 
 /// Looks up the glyph for `c` and returns its index alongside its width at the
 /// given `size`.
-fn lookup_glyph(face: &Face, c: char, size: f64) -> Option<(GlyphId, f64)> {
+fn lookup_glyph(face: &Face, c: char, size: Length) -> Option<(GlyphId, Length)> {
     let glyph = face.glyph_index(c)?;
 
     // Determine the width of the char.
diff --git a/src/syntax/ast/lit.rs b/src/syntax/ast/lit.rs
index 4370345a..40b360da 100644
--- a/src/syntax/ast/lit.rs
+++ b/src/syntax/ast/lit.rs
@@ -3,7 +3,7 @@
 use super::*;
 use crate::color::RgbaColor;
 use crate::eval::DictKey;
-use crate::length::Length;
+use crate::geom::Unit;
 
 /// A literal.
 #[derive(Debug, Clone, PartialEq)]
@@ -17,13 +17,13 @@ pub enum Lit {
     /// A floating-point literal: `1.2`, `10e-4`.
     Float(f64),
     /// A length literal: `12pt`, `3cm`.
-    Length(Length),
+    Length(f64, Unit),
     /// A percent literal: `50%`.
     ///
-    /// _Note_: `50%` is represented as `50.0` here, but as `0.5` in the
+    /// _Note_: `50%` is stored as `50.0` here, but as `0.5` in the
     /// corresponding [value].
     ///
-    /// [value]: ../../eval/enum.Value.html#variant.Relative
+    /// [value]: ../../geom/struct.Relative.html
     Percent(f64),
     /// A color literal: `#ffccee`.
     Color(RgbaColor),
diff --git a/src/syntax/token.rs b/src/syntax/token.rs
index cb0526c1..5b055e39 100644
--- a/src/syntax/token.rs
+++ b/src/syntax/token.rs
@@ -1,6 +1,6 @@
 //! Token definition.
 
-use crate::length::Length;
+use crate::geom::Unit;
 
 /// A minimal semantic entity of source code.
 #[derive(Debug, Copy, Clone, PartialEq)]
@@ -72,10 +72,10 @@ pub enum Token<'s> {
     /// A floating-point number: `1.2`, `10e-4`.
     Float(f64),
     /// A length: `12pt`, `3cm`.
-    Length(Length),
+    Length(f64, Unit),
     /// A percentage: `50%`.
     ///
-    /// _Note_: `50%` is represented as `50.0` here, as in the corresponding
+    /// _Note_: `50%` is stored as `50.0` here, as in the corresponding
     /// [literal].
     ///
     /// [literal]: ../ast/enum.Lit.html#variant.Percent
@@ -159,7 +159,7 @@ impl<'s> Token<'s> {
             Self::Bool(_) => "bool",
             Self::Int(_) => "integer",
             Self::Float(_) => "float",
-            Self::Length(_) => "length",
+            Self::Length(..) => "length",
             Self::Percent(_) => "percentage",
             Self::Hex(_) => "hex value",
             Self::Str { .. } => "string",
diff --git a/tests/test_typeset.rs b/tests/test_typeset.rs
index 52f7a1fa..3789d978 100644
--- a/tests/test_typeset.rs
+++ b/tests/test_typeset.rs
@@ -15,7 +15,7 @@ use typstc::diag::{Feedback, Pass};
 use typstc::eval::State;
 use typstc::export::pdf;
 use typstc::font::{FontLoader, SharedFontLoader};
-use typstc::geom::{Point, Vec2};
+use typstc::geom::{Length, Point};
 use typstc::layout::{BoxLayout, LayoutElement};
 use typstc::parse::LineMap;
 use typstc::shaping::Shaped;
@@ -138,43 +138,40 @@ impl TestFilter {
 }
 
 fn render(layouts: &[BoxLayout], loader: &FontLoader, scale: f64) -> DrawTarget {
-    let pad = scale * 10.0;
+    let pad = Length::pt(scale * 10.0);
     let width = 2.0 * pad
         + layouts
             .iter()
             .map(|l| scale * l.size.width)
             .max_by(|a, b| a.partial_cmp(&b).unwrap())
-            .unwrap()
-            .round();
+            .unwrap();
 
-    let height = pad
-        + layouts
-            .iter()
-            .map(|l| scale * l.size.height + pad)
-            .sum::<f64>()
-            .round();
+    let height =
+        pad + layouts.iter().map(|l| scale * l.size.height + pad).sum::<Length>();
 
-    let mut surface = DrawTarget::new(width as i32, height as i32);
+    let int_width = width.to_pt().round() as i32;
+    let int_height = height.to_pt().round() as i32;
+    let mut surface = DrawTarget::new(int_width, int_height);
     surface.clear(BLACK);
 
-    let mut offset = Vec2::new(pad, pad);
+    let mut offset = Point::new(pad, pad);
     for layout in layouts {
         surface.fill_rect(
-            offset.x as f32,
-            offset.y as f32,
-            (scale * layout.size.width) as f32,
-            (scale * layout.size.height) as f32,
+            offset.x.to_pt() as f32,
+            offset.y.to_pt() as f32,
+            (scale * layout.size.width).to_pt() as f32,
+            (scale * layout.size.height).to_pt() as f32,
             &Source::Solid(WHITE),
             &Default::default(),
         );
 
-        for (pos, element) in &layout.elements {
+        for &(pos, ref element) in &layout.elements {
             match element {
                 LayoutElement::Text(shaped) => render_shaped(
                     &mut surface,
                     loader,
                     shaped,
-                    (scale * pos.to_vec2() + offset).to_point(),
+                    scale * pos + offset,
                     scale,
                 ),
             }
@@ -205,8 +202,8 @@ fn render_shaped(
         let x = pos.x + scale * offset;
         let y = pos.y + scale * shaped.size;
 
-        let t = Transform::create_scale(s as f32, -s as f32)
-            .post_translate(Vector::new(x as f32, y as f32));
+        let t = Transform::create_scale(s.to_pt() as f32, -s.to_pt() as f32)
+            .post_translate(Vector::new(x.to_pt() as f32, y.to_pt() as f32));
 
         surface.fill(
             &path.transform(&t),