2 files changed, 33 insertions, 4 deletions
diff --git a/src/model/layout.rs b/src/model/layout.rs
index 51154286..3b82ddc2 100644
--- a/src/model/layout.rs
+++ b/src/model/layout.rs
@@ -8,8 +8,10 @@ use std::sync::Arc;
 use super::{Barrier, NodeId, Resolve, StyleChain, StyleEntry};
 use crate::diag::TypResult;
 use crate::eval::{RawAlign, RawLength};
-use crate::frame::{Element, Frame, Geometry};
-use crate::geom::{Align, Length, Paint, Point, Relative, Sides, Size, Spec, Stroke};
+use crate::frame::{Element, Frame};
+use crate::geom::{
+    Align, Geometry, Length, Paint, Point, Relative, Sides, Size, Spec, Stroke,
+};
 use crate::library::graphics::MoveNode;
 use crate::library::layout::{AlignNode, PadNode};
 use crate::util::Prehashed;
diff --git a/src/model/styles.rs b/src/model/styles.rs
index eb7a7053..ae4c1586 100644
--- a/src/model/styles.rs
+++ b/src/model/styles.rs
@@ -7,8 +7,8 @@ use std::sync::Arc;
 
 use super::{Content, Show, ShowNode};
 use crate::diag::{At, TypResult};
-use crate::eval::{Args, Func, Node, Smart, Value};
-use crate::geom::{Numeric, Relative, Sides, Spec};
+use crate::eval::{Args, Func, Node, RawLength, Smart, Value};
+use crate::geom::{Length, Numeric, Relative, Sides, Spec};
 use crate::library::layout::PageNode;
 use crate::library::structure::{EnumNode, ListNode};
 use crate::library::text::{FontFamily, ParNode, TextNode};
@@ -459,6 +459,33 @@ where
     }
 }
 
+impl<T> Fold for Sides<T>
+where
+    T: Fold,
+{
+    type Output = Sides<T::Output>;
+
+    fn fold(self, outer: Self::Output) -> Self::Output {
+        self.zip(outer, |inner, outer, _| inner.fold(outer))
+    }
+}
+
+impl Fold for Sides<Option<Relative<Length>>> {
+    type Output = Sides<Relative<Length>>;
+
+    fn fold(self, outer: Self::Output) -> Self::Output {
+        self.zip(outer, |inner, outer, _| inner.unwrap_or(outer))
+    }
+}
+
+impl Fold for Sides<Option<Smart<Relative<RawLength>>>> {
+    type Output = Sides<Smart<Relative<RawLength>>>;
+
+    fn fold(self, outer: Self::Output) -> Self::Output {
+        self.zip(outer, |inner, outer, _| inner.unwrap_or(outer))
+    }
+}
+
 /// A scoped property barrier.
 ///
 /// Barriers interact with [scoped](StyleMap::scoped) styles: A scoped style