path: root/docs/theming-guide.adoc

= Asciidoctor PDF Theming Guide
Dan Allen <https://github.com/mojavelinux[@mojavelinux]>
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Topics remaining to document:
* line height and line height length (and what that all means)
* title page layout / title page images (logo & background)
* document that unicode escape sequences can be used inside double-quoted strings
////

[.lead]
The theming system in Asciidoctor PDF is used to control the layout and styling of the PDF file Asciidoctor PDF generates from AsciiDoc.
This document describes how the theming system works, how to define a custom theme in YAML and how to activate the theme when running Asciidoctor PDF.

TIP: The quickest way to create your own theme is to <<Extends,extend the default theme>>.
This not only gives you a set of foundation styles to build on, it also provides a collection of <<Bundled Fonts,bundled fonts>>.
If you want to replace the bundled fonts with your own, you must declare the name and location of each font in the <<Custom fonts,font catalog>>.
To reuse the bundled fonts, you can either extend the default theme and/or redeclare the bundled fonts in the font catalog.

WARNING: If you don't declare your own fonts (or extend the default theme), only the built-in (AFM) fonts provided by the PDF reader will be available.
Using AFM fonts can result in missing functionality and warnings.
See the <<Built-In (AFM) Fonts>> section to learn more about these limitations.

toc::[]

== Language Overview

The Asciidoctor PDF theme language is described using the http://en.wikipedia.org/wiki/YAML[YAML] data format and incorporates many _concepts_ from CSS and SASS.
Therefore, if you have a background in web design, the terminology should be immediately familiar to you.
*Note, however, that the theming system isn't actually CSS.*

Like CSS, themes have both selectors and properties.
Selectors are the component you want to style.
The properties are the style elements of that component that can be styled.
All selector names are implicit (e.g., `heading`), so you customize the theme primarily by manipulating pre-defined property values (e.g., `font-size`).

[NOTE]
====
The theme language in Asciidoctor PDF supports a limited subset of the properties from CSS.
Some of these properties have different names from those found in CSS.

* An underscore (`_`) may be used in place of a hyphen (`-`) in all property names (so you may use `font_family` or `font-family`).
* An underscore (`_`) may be used in place of a hyphen (`-`) in all variable names (so you may use `$base_font_family` or `$base-font-family`).
* Instead of separate properties for font weight and font style, the theme language combines these settings in the `font-style` property (allowed values: `normal`, `bold`, `italic` and `bold_italic`).
* The `align` property in the theme language is roughly equivalent to the `text-align` property in CSS.
* The `font-color` property in the theme language is equivalent to the `color` property in CSS.
====

A theme is described in a YAML-based data format and stored in a dedicated theme file.
YAML is a human-friendly data format that resembles CSS and helps to describe the theme.
The theme language adds some extra features to YAML, such as variables, basic math, measurements and color values.
These enhancements will be explained in detail in later sections.

The theme file must be named _<name>-theme.yml_, where `<name>` is the name of the theme.
_We recommend *not* using the names *base* or *default* so you don't confuse it with one of the built-in themes._

Here's an example of a basic theme file that extends the base theme:

.basic-theme.yml
[source,yaml]
----
page:
  layout: portrait
  margin: [0.75in, 1in, 0.75in, 1in]
  size: Letter
base:
  font-color: #333333
  font-family: Times-Roman
  font-size: 12
  line-height-length: 17
  line-height: $base-line-height-length / $base-font-size
vertical-spacing: $base-line-height-length
heading:
  font-color: #262626
  font-size: 17
  font-style: bold
  line-height: 1.2
  margin-bottom: $vertical-spacing
link:
  font-color: #002FA7
outline-list:
  indent: $base-font-size * 1.5
footer:
  height: $base-line-height-length * 2.5
  line-height: 1
  recto:
    right:
      content: '{page-number}'
  verso:
    left:
      content: $footer-recto-right-content
----

When creating a new theme, you only have to define the keys you want to override from the base theme, which is loaded prior to loading your custom theme.
All the available keys are documented in <<Keys>>.
The converter uses the information from the theme map to help construct the PDF.

Instead of designing a theme from scratch, you can extend the default theme using the `extends` key as follows:

[source,yaml]
----
extends: default
base:
  font-color: #ff0000
----

You can also point the extends key at another custom theme to extend from it.
If you don't want to extend any theme, including the base theme, assign the value `~` to the `extends` key (i.e., `extends: ~`).

WARNING: If you start a new theme from scratch, we strongly recommend defining TrueType fonts and specifying them in the `base` and `literal` categories.
Otherwise, Asciidoctor PDF will use built-in AFM fonts, which can result in missing functionality and warnings.

[TIP]
====
Instead of creating a theme from scratch, another option is to download the https://github.com/asciidoctor/asciidoctor-pdf/blob/master/data/themes/default-theme.yml[default-theme.yml] file from the source repository.
Save the file using a unique name (e.g., _custom-theme.yml_) and start hacking on it.

Alternatively, you can snag the file from your local installation using the following command:

 $ ASCIIDOCTOR_PDF_DIR=`gem contents asciidoctor-pdf --show-install-dir`;\
   cp "$ASCIIDOCTOR_PDF_DIR/data/themes/default-theme.yml" custom-theme.yml
====

Keys may be nested to an arbitrary depth to eliminate redundant prefixes (an approach inspired by SASS).
Once the theme is loaded, all keys are flattened into a single map of qualified keys.
Nesting is simply a shorthand way of organizing the keys.
In the end, a theme is just a map of key/value pairs.

Nested keys are adjoined to their parent key with an underscore (`_`) or hyphen (`-`).
This means the selector part (e.g., `link`) is combined with the property name (e.g., `font-color`) into a single, qualified key (e.g., `link_font_color` or `link-font-color`).

For example, let's assume we want to set the base (i.e., global) font size and color.
These keys may be written longhand:

[source,yaml]
----
base-font-color: #333333
base-font-family: Times-Roman
base-font-size: 12
----

Or, to avoid having to type the prefix `base-` multiple times, the keys may be written as a hierarchy:

[source,yaml]
----
base:
  font-color: #333333
  font-family: Times-Roman
  font-size: 12
----

Or even:

[source,yaml]
----
base:
  font:
    color: #333333
    family: Times-Roman
    size: 12
----

Each level of nesting must be indented by two spaces from the indentation of the parent level.
Also note the presence of the colon (`:`) after each key name.

== Values

The value of a key may be one of the following types:

* String
 ** Font family name (e.g., Roboto)
 ** Font style (normal, bold, italic, bold_italic)
 ** Alignment (left, center, right, justify)
 ** Color as hex string (e.g., 'ff0000', #ff0000, or '#ff0000')
 ** Image path
 ** Enumerated type (where specified)
 ** Text content (where specified)
* Null (clears any previously assigned value)
 ** _empty_ (i.e., no value specified)
 ** null
 ** ~
* Number (integer or float) with optional units (default unit is points)
* Array
 ** Color as RGB array (e.g., [51, 51, 51])
 ** Color CMYK array (e.g., [50, 100, 0, 0])
 ** Margin (e.g., [1in, 1in, 1in, 1in])
 ** Padding (e.g., [1in, 1in, 1in, 1in])
* Variable reference (e.g., $base_font_color or $base-font-color)
* Math expression

Note that keys almost always require a value of a specific type, as documented in <<Keys>>.

=== Inheritance

Like CSS, inheritance is a principle feature in the Asciidoctor PDF theme language.
For many of the properties, if a key is not specified, the key inherits the value applied to the parent content in the content hierarchy.
This behavior saves you from having to specify properties unless you want to override the inherited value.

The following keys are inherited:

* font-family
* font-color
* font-size
* font-style
* text-transform
* line-height (currently some exceptions)
* margin-bottom (if not specified, defaults to $vertical-spacing)

.Heading Inheritance
****
Headings inherit starting from a specific heading level (e.g., `heading-h2-font-size`), then to the heading category (e.g., `heading-font-size`), then directly to the base value (e.g., `base-font-size`).
Any setting from an enclosing context, such as a sidebar, is skipped.
****

=== Variables

To save you from having to type the same value in your theme over and over, or to allow you to base one value on another, the theme language supports variables.
Variables consist of the key name preceded by a dollar sign (`$`) (e.g., `$base-font-size`).
Any qualified key that has already been defined can be referenced in the value of another key.
(In order words, as soon as the key is assigned, it's available to be used as a variable).

IMPORTANT: Variables are defined from top to bottom (i.e., in document order).
Therefore, a variable must be defined before it is referenced.
In other words, the path the variable refers to must be *above* the usage of that variable.

For example, once the following line is processed,

[source,yaml]
----
base:
  font-color: #333333
----

the variable `$base-font-color` will be available for use in subsequent lines and will resolve to `#333333`.

Let's say you want to make the font color of the sidebar title the same as the heading font color.
Just assign the value `$heading-font-color` to the `$sidebar-title-font-color`.

[source,yaml]
----
heading:
  font-color: #191919
sidebar:
  title:
    font-color: $heading-font-color
----

You can also use variables in math expressions to use one value to build another.
This is commonly done to set font sizes proportionally.
It also makes it easy to test different values very quickly.

[source,yaml]
----
base:
  font-size: 12
  font-size-large: $base-font-size * 1.25
  font-size-small: $base-font-size * 0.85
----

We'll cover more about math expressions later.

==== Custom Variables

You can define arbitrary key names to make custom variables.
This is one way to group reusable values at the top of your theme file.
If you are going to do this, it's recommended that you organize the keys under a custom namespace, such as `brand`.

For instance, here's how you can define your brand colors:

[source,yaml,subs=attributes+]
----
brand:
  primary-color: #E0162B {conum-guard-yaml} <1>
  secondary-color: '#FFFFFF' {conum-guard-yaml} <2>
  alert-color: '0052A5' {conum-guard-yaml} <3>
----
<1> To align with CSS, you may add `+#+` in front of the hex color value to coerce it to a string.
A YAML preprocessor is used to ensure the value is not treated as a comment as would normally be the case in YAML.
<2> You may put quotes around the CSS-style hex value to make it friendly to a YAML editor or validation tool.
<3> The leading `+#+` on a hex value is entirely optional.
However, we recommend that you always use either a leading `+#+` or surrounding quotes (or both) to prevent YAML from mangling the value (for example, 000000 would become 0, so use '000000' or #000000 instead).

You can now use these custom variables later in the theme file:

[source,yaml]
----
base:
  font-color: $brand-primary-color
----

=== Math Expressions & Functions

The theme language supports basic math operations to support calculated values.
Like programming languages, multiple and divide take precedence over add and subtract.

The following table lists the supported operations and the corresponding operator for each.

[width=25%]
|===
|Operation |Operator

|multiply
|*

|divide
|/

|add
|+

|subtract
|-
|===

IMPORTANT: Operators must always be surrounded by a space on either side (e.g., 2 + 2, not 2+2).

Here's an example of a math expression with fixed values.

[source,yaml]
----
conum:
  line-height: 4 / 3
----

Variables may be used in place of numbers anywhere in the expression:

[source,yaml]
----
base:
  font-size: 12
  font-size-large: $base-font-size * 1.25
----

Values used in a math expression are automatically coerced to a float value before the operation.
If the result of the expression is an integer, the value is coerced to an integer afterwards.

IMPORTANT: Numeric values less than 1 must have a 0 before the decimal point (e.g., 0.85).

The theme language also supports several functions for rounding the result of a math expression.
The following functions may be used if they surround the whole value or expression for a key.

round(...):: Rounds the number to the nearest half integer.
floor(...):: Rounds the number up to the next integer.
ceil(...):: Rounds the number down the previous integer.

You might use these functions in font size calculations so that you get more exact values.

[source,yaml]
----
base:
  font-size: 12.5
  font-size-large: ceil($base-font-size * 1.25)
----

=== Measurement Units

Several of the keys require a value in points (pt), the unit of measure for the PDF canvas.
A point is defined as 1/72 of an inch.
If you specify a number without any units, the units defaults to pt.

However, us humans like to think in real world units like inches (in), centimeters (cm), or millimeters (mm).
You can let the theme do this conversion for you automatically by adding a unit notation next to any number.

The following units are supported:

[width=25%]
|===
|Unit |Suffix

|Centimeter
|cm

|Inches
|in

|Millimeter
|mm

|Percentage^[1]^
|%, vw, or vh

|Points
|pt (default)
|===

. A percentage with the % unit is calculated relative to the width or height of the content area.
Viewport-relative percentages (vw or vh units) are calculated as a percentage of the page width or height, respectively.
Currently, percentage units can only be used for placing elements on the title page or for setting the width of a block image.

Here's an example of how you can use inches to define the page margins:

[source,yaml]
----
page:
  margin: [0.75in, 1in, 0.75in, 1in]
----

The order of elements in a measurement array is the same as it is in CSS:

. top
. right
. bottom
. left

=== Alignments

The align subkey is used to align text and images within the parent container.

==== Text Alignments

Text can be aligned as follows:

* left
* center
* right
* justify (stretched to each edge)

==== Image Alignments

Images can be aligned as follows:

* left
* center
* right

=== Font Styles

In most cases, whereever you can specify a custom font family, you can also specify a font style.
These two settings are combined to locate the font to use.

The following font styles are recognized:

* normal (no style)
* italic
* bold
* bold_italic

=== Text Transforms

Many places where font properties can be specified, a case transformation can be applied to the text.
The following transforms are recognized:

* uppercase
* lowercase
* none (clears an inherited value)

[CAUTION#transform-unicode-letters]
====
Since Ruby 2.4, Ruby has built-in support for transforming the case of any letter defined by Unicode.

If you're using Ruby < 2.4, and the text you want to transform contains characters beyond the Basic Latin character set (e.g., an accented character), you must install either the `activesupport` or the `unicode` gem in order for those characters to be transformed.

 $ gem install activesupport

or

 $ gem install unicode
====

// Additional transforms, such as capitalize, may be added in the future.

=== Colors

The theme language supports color values in three formats:

Hex:: A string of 3 or 6 characters with an optional leading `#`, optional surrounding quotes, or both.
RGB:: An array of numeric values ranging from 0 to 255.
CMYK:: An array of numeric values ranging from 0 to 1 or from 0% to 100%.
Transparent:: The special value `transparent` indicates that a color should not be used.

==== Hex

The hex color value is likely most familiar to web developers.
The value must be either 3 or 6 characters (case insensitive) with an optional leading hash (`#`), optional surrounding quotes, or both.

To align with CSS, you may add a `+#+` in front of the hex color value.
A YAML preprocessor is used to ensure the value is not treated as a comment as would normally be the case in YAML.
That same preprocessor will also coerce a primitive value to a string if `color` is the name of the last segment in the key (e.g., `font-color`).
This avoids the problem of 000 becoming 0 (and similar implicit conversions) when the theme file is parsed.

You also may put quotes around the CSS-style hex value to make it friendly to a YAML editor or validation tool.
In this case, the leading `+#+` on a hex value is entirely optional.

Regardless, we recommend that you always use either a leading `+#+` or surrounding quotes (or both) to prevent YAML from mangling the value.

The following are all equivalent values for the color red:

[cols="8*m"]
|===
|#ff0000
|#FF0000
|'ff0000'
|'FF0000'
|#f00
|#F00
|'f00'
|'F00'
|===

Here's how a hex color value appears in the theme file:

[source,yaml]
----
base:
  font-color: #ff0000
----

==== RGB

An RGB array value must be three numbers ranging from 0 to 255.
The values must be separated by commas and be surrounded by square brackets.

NOTE: An RGB array is automatically converted to a hex string internally, so there's no difference between ff0000 and [255, 0, 0].

Here's how to specify the color red in RGB:

* [255, 0, 0]

Here's how a RGB color value appears in the theme file:

[source,yaml]
----
base:
  font-color: [255, 0, 0]
----

==== CMYK

A CMYK array value must be four numbers ranging from 0 and 1 or from 0% to 100%.
The values must be separated by commas and be surrounded by square brackets.

Unlike the RGB array, the CMYK array _is not_ converted to a hex string internally.
PDF has native support for CMYK colors, so you can preserve the original color values in the final PDF.

Here's how to specify the color red in CMYK:

* [0, 0.99, 1, 0]
* [0, 99%, 100%, 0]

Here's how a CMYK color value appears in the theme file:

[source,yaml]
----
base:
  font-color: [0, 0.99, 1, 0]
----

==== Transparent

It's possible to specify no color by assigning the special value `transparent`, as shown here:

[source,yaml]
----
table:
  background-color: transparent
----

=== Images

An image is specified either as a bare image path or as an inline image macro as found in the AsciiDoc syntax.
Images in the theme file are currently resolved relative to the value of the `pdf-themesdir` attribute.
(If `pdf-theme` is a path that ends in `.yml`, and `pdf-themesdir` is not set, then the images are resolved relative to the directory of the path specified by `pdf-theme`).

The following image types (and corresponding file extensions) are supported:

* PNG (.png)
* JPEG (.jpg)
* SVG (.svg)

CAUTION: The GIF format (.gif) and BMP format (.bmp) are not supported unless you're using prawn-gmagick.
See https://github.com/asciidoctor/asciidoctor-pdf#supporting-additional-image-file-formats[support for additional image file formats] for details.

Here's how an image is specified in the theme file as a bare image path:

[source,yaml]
----
title-page:
  background-image: title-cover.png
----

Here's how the image is specified using the inline image macro:

[source,yaml]
----
title-page:
  background-image: image:title-cover.png[]
----

In either case, the image is resolved relative to the value of the `pdf-themesdir` attribute, as previously described.

Like in the AsciiDoc syntax, wrapping the value in the image macro allows you to specify other settings, such as `pdfwidth`, `fit`, and/or `align`.
For example:

[source,yaml]
----
title-page:
  logo-image: image:logo.png[width=250,align=center]
----

=== Quoted String

Some of the keys accept a quoted string as text content.
The final segment of these keys is always named `content`.

A content key accepts a string value.
It's usually best to quote the string or use the http://symfony.com/doc/current/components/yaml/yaml_format.html#strings[YAML multi-line string syntax].

Text content may be formatted using a subset of inline HTML.
You can use the well-known elements such as `<strong>`, `<em>`, `<code>`, `<a>`, `<sub>`, `<sup>`, `<del>`, and `<span>`.
The `<span>` element supports the `style` attribute, which you can use to specify the `color`, `font-weight`, and `font-style` CSS properties.
You can also use the `rgb` attribute on the `<color>` element to change the color or the `name` and `size` attributes on the `<font>` element to change the font properties.
If you need to add an underline or strikethrough decoration to the text, you can assign the `underline` or `line-through` to the `class` attribute on any aforementioned element.

Here's an example of using formatting in the content of the menu caret:

[source,yaml]
----
menu-caret-content: " <font size=\"1.15em\"><color rgb=\"#b12146\">\u203a</color></font> "
----

NOTE: The string must be double quoted in order to use a Unicode escape code like `\u203a`.

Additionally, normal substitutions are applied to the value of content keys for <<Running Content (Header & Footer),running content>>, so you can use most AsciiDoc inline formatting (e.g., `+*strong*+` or `+{attribute-name}+`) in the values of those keys.

== Fonts

You can select from <<built-in-afm-fonts,built-in PDF fonts>>, <<bundled-fonts,fonts bundled with Asciidoctor PDF>> or <<custom-fonts,custom fonts>> loaded from TrueType font (TTF) files.
If you want to use custom fonts, you must first declare them in your theme file.

IMPORTANT: Asciidoctor has no challenge working with Unicode.
In fact, it prefers Unicode and considers the entire range.
However, once you convert to PDF, you have to meet the font requirements of PDF in order to preserve Unicode characters.
That means you need to provide a font (at least a fallback font) that contains glyphs for all the characters you want to use.
If you don't, you may notice that characters are missing (usually replaced with a box).
There's nothing Asciidoctor can do to convince PDF to work with extended characters without the right fonts in play.

=== Built-In (AFM) Fonts

The names of the built-in fonts (for general-purpose text) are as follows:

[width=33.33%]
|===
|Font Name |Font Family

|Helvetica
|sans-serif

|Times-Roman
|serif

|Courier
|monospace
|===

Using a built-in font requires no additional files.
You can use the key anywhere a `font-family` property is accepted in the theme file.
For example:

[source,yaml]
----
base:
  font-family: Times-Roman
----

However, when you use a built-in font, the characters you can use in your document are limited to the characters in the WINANSI (http://en.wikipedia.org/wiki/Windows-1252[Windows-1252]) code set.
WINANSI includes most of the characters needed for writing in Western languages (English, French, Spanish, etc).
For anything outside of that, PDF is BYOF (Bring Your Own Font).

Even though the built-in fonts require the content to be encoded in WINANSI, _you still type your AsciiDoc document in UTF-8_.
Asciidoctor PDF encodes the content into WINANSI when building the PDF.

WARNING: Built-in (AFM) fonts do not use the <<fallback-fonts,fallback fonts>>.
In order for the fallback font to kick in, you must be using a TrueType font.

.WINANSI Encoding Behavior
****
When using the built-in PDF (AFM) fonts on a block of content in your AsciiDoc document, any character that cannot be encoded to WINANSI is replaced with a logic "`not`" glyph (`&#172;`) and you'll see the following warning in your console:

 The following text could not be fully converted to the Windows-1252 character set:
 | <string with unknown glyph>

This behavior differs from the default behavior in Prawn, which is to simply crash.

You'll often see this warning if you're using callouts in your document and you haven't specified a TrueType font in your theme.
To prevent this warning, you need to specify a TrueType font.

When using a TrueType font, you will get no warning for a missing glyph.
That's a consequence of how Prawn works and is outside of Asciidoctor PDF's control.
However, you'll likely see it substituted with a box (guaranteed if you're using one of the bundled fonts).

For more information about how Prawn handles character encodings for built-in fonts, see https://github.com/prawnpdf/prawn/blob/master/CHANGELOG.md#vastly-improved-handling-of-encodings-for-pdf-built-in-afm-fonts[this note in the Prawn CHANGELOG].
****

=== Bundled Fonts

Asciidoctor PDF bundles several fonts that are used by the default theme.
You can also use these fonts in your custom theme by simply declaring them.
These fonts provide more characters than the built-in PDF fonts, but still only a subset of UTF-8 (to reduce the size of the gem).

The family name of the fonts bundled with Asciidoctor PDF are as follows:

http://www.google.com/get/noto/#/family/noto-serif[Noto Serif]::
A serif font that can be styled as normal, italic, bold or bold_italic.

http://mplus-fonts.osdn.jp/mplus-outline-fonts/design/index-en.html#mplus_1mn[M+ 1mn]::
A monospaced font that maps different thicknesses to the styles normal, italic, bold and bold_italic.
Also provides the circuled numbers used in callouts.

http://mplus-fonts.osdn.jp/mplus-outline-fonts/design/index-en.html#mplus_1p[M+ 1p Fallback]::
A sans-serif font that provides a very complete set of Unicode glyphs.
Cannot be styled as italic, bold or bold_italic.
Used as the fallback font in the `default-with-fallback-font` theme.

TIP: If you want to specify the location of custom fonts using the `pdf-fontsdir` attribute, yet still be able to use the bundled fonts, you need to refer to the bundled fonts using the `GEM_FONTS_DIR` token.
To do so, you can either a) prefix the path of the bundled font in the theme file with the segment `GEM_FONTS_DIR` (e.g., `GEM_FONTS_DIR/mplus1p-regular-fallback.ttf`, or b) include `GEM_FONT_DIR` in the value of the `pdf-fontsdir` attribute, separated from the location of your custom fonts by a semi-colon (e.g., `path/to/your/fonts;GEM_FONTS_DIR`).

=== Custom Fonts

The limited character set of WINANSI, or the bland look of the built-in fonts, may motivate you to load your own font.
Custom fonts can enhance the look of your PDF theme substantially.

To start, find the TTF file collection for the font you want to use.
A collection typically consists of all four font styles:

* normal
* italic
* bold
* bold_italic

You'll need all four styles to support AsciiDoc content properly.
_Asciidoctor PDF cannot italicize a font dynamically like a browser can, so the italic styles are required._

In order for a third-party font to work properly with Prawn (and hence Asciidoctor PDF), several modifications are required.
See <<Prepare a Custom Font>> to learn how to prepare your font for use with Asciidoctor PDF.

Once you've obtained the TTF files, put them in the directory inside your project where you want to store the fonts.
It's recommended that you name them consistently so it's easier to type the names in the theme file.

Let's assume the name of the font is https://github.com/google/roboto/tree/master/out/RobotoTTF[Roboto].
Rename the files as follows:

* roboto-normal.ttf (_originally Roboto-Regular.ttf_)
* roboto-italic.ttf (_originally Roboto-Italic.ttf_)
* roboto-bold.ttf (_originally Roboto-Bold.ttf_)
* roboto-bold_italic.ttf (_originally Roboto-BoldItalic.ttf_)

Next, declare the font under the `font-catalog` key at the top of your theme file, giving it a unique key (e.g., `Roboto`).

[source,yaml]
----
font:
  catalog:
    Roboto:
      normal: roboto-normal.ttf
      italic: roboto-italic.ttf
      bold: roboto-bold.ttf
      bold_italic: roboto-bold_italic.ttf
----

You can use the key that you assign to the font in the font catalog anywhere the `font-family` property is accepted in the theme file.
For example, to use the Roboto font for all headings, use:

[source,yaml]
----
heading:
  font-family: Roboto
----

When you execute Asciidoctor PDF, specify the directory where the fonts reside using the `pdf-fontsdir` attribute:

 $ asciidoctor-pdf -a pdf-theme=basic-theme.yml -a pdf-fontsdir=path/to/fonts document.adoc

You can specify multiple directories by separating the entries with a semi-colon:

 $ asciidoctor-pdf -a pdf-theme=basic-theme.yml -a pdf-fontsdir=path/to/fonts;path/to/more-fonts document.adoc

To include the bundled fonts in the search, use the `GEM_FONTS_DIR` token:

 $ asciidoctor-pdf -a pdf-theme=basic-theme.yml -a pdf-fontsdir=path/to/fonts;GEM_FONTS_DIR document.adoc

TIP: When Asciidoctor PDF creates the PDF, it only embeds the glyphs from the font that are needed to render the characters present in the document.
Effectively, it subsets the font.
While that saves space taken up by the generated PDF, you may still be storing the full font in your source repository.
To minimize the size of the source font, you can use {url-fontforge}[FontForge] to subset the font ahead of time.
Subsetting a font means remove glyphs you don't plan to use.
Doing so it not a requirement, simply a personal preference.

You can add any number of fonts to the catalog.
Each font must be assigned a unique key, as shown here:

[source,yaml]
----
font:
  catalog:
    Roboto:
      normal: roboto-normal.ttf
      italic: roboto-italic.ttf
      bold: roboto-bold.ttf
      bold_italic: roboto-bold_italic.ttf
    Roboto Light:
      normal: roboto-light-normal.ttf
      italic: roboto-light-italic.ttf
      bold: roboto-light-bold.ttf
      bold_italic: roboto-light-bold_italic.ttf
----

Text in SVGs will use the font catalog from your theme.
We recommend that you match the font key in your theme file to the name of the font seen by the operating system.
This will allow you to use the same font names (aka families) in both your graphics program and Asciidoctor PDF, thus making them portable.

=== Fallback Fonts

If a TrueType font is missing a character needed to render the document, such as a special symbol, you can have Asciidoctor PDF look for the character in a fallback font.
You only need to specify a single fallback font, typically one that provides a full set of symbols.
If the character isn't found in the fallback font, it will mostly likely be replaced by a box (guaranteed if you're using the bundled fallback font).

IMPORTANT: The fallback font only gets used when the primary font is a TrueType font (i.e., TTF, DFont, TTC).
Any glyph missing from an AFM font is simply replaced with the "`not`" glyph (`&#172;`).

CAUTION: The `default` theme does not use a fallback font.
However, the built-in `default-with-fallback-font` theme does.
Using the fallback font slows down PDF generation slightly because it has to analyze every single character.
It's use is not recommended for large documents.
Instead, it's best to select primary fonts that have all the characters you need.

Like with other custom fonts, you first need to declare the fallback font.
Let's choose https://github.com/android/platform_frameworks_base/blob/master/data/fonts/DroidSansFallback.ttf[Droid Sans Fallback].
You can map all the styles to a single font file (since bold and italic don't usually make sense for symbols).

[source,yaml]
----
font:
  catalog:
    Roboto:
      normal: roboto-normal.ttf
      italic: roboto-italic.ttf
      bold: roboto-bold.ttf
      bold_italic: roboto-bold_italic.ttf
    DroidSansFallback:
      normal: droid-sans-fallback.ttf
      italic: droid-sans-fallback.ttf
      bold: droid-sans-fallback.ttf
      bold_italic: droid-sans-fallback.ttf
----

Next, add the key name to the `fallbacks` key under the `font-catalog` key.
The `fallbacks` key accepts an array of values, meaning you can specify more than one fallback font.
However, we recommend using a single fallback font, if possible, as shown here:

[source,yaml]
----
font:
  catalog:
    Roboto:
      normal: roboto-normal.ttf
      italic: roboto-italic.ttf
      bold: roboto-bold.ttf
      bold_italic: roboto-bold_italic.ttf
    DroidSansFallback:
      normal: droid-sans-fallback.ttf
      italic: droid-sans-fallback.ttf
      bold: droid-sans-fallback.ttf
      bold_italic: droid-sans-fallback.ttf
  fallbacks:
  - DroidSansFallback
----

TIP: If you are using more than one fallback font, add additional lines to the `fallbacks` key.

Of course, make sure you've configured your theme to use your custom font:

[source,yaml]
----
base:
  font-family: Roboto
----

That's it!
Now you're covered.
If your custom TTF font is missing a glyph, Asciidoctor PDF will look in your fallback font.
You don't need to reference the fallback font anywhere else in your theme file.

== Keys

This section lists all the keys that are available when creating a custom theme.
The keys are organized by category.
Each category represents a common prefix under which the keys are typically nested.

TIP: Keys can be nested wherever an underscore (`_`) or hyphen (`-`) appears in the name.
This nested structure is for organizational purposes only.
All keys are flatted when the theme is loaded (e.g., `align` nested under `base` becomes `base-align`).

The converter uses the values of these keys to control how most elements are arranged and styled in the PDF.
The default values listed in this section get inherited from the https://github.com/asciidoctor/asciidoctor-pdf/blob/master/data/themes/base-theme.yml[base theme].

IMPORTANT: The https://github.com/asciidoctor/asciidoctor-pdf/blob/master/data/themes/default-theme.yml[default theme] has a different set of values which are not shown in this guide.

When creating a theme, all keys are optional.
Required keys are provided by the base theme.
Therefore, you only have to declare keys that you want to override.

[#keys-extends]
=== Extends

A theme can extend another theme using the `extends` key.
For example:

[source,yaml]
----
extends: default
base:
  font-color: #ff0000
----

The extends key accepts either a single value or an array of values.
Each value is interpreted as a filename.
If the filename equals `default`, it resolves to the location of the default (built-in) theme.
If the filename is absolute, it's used as is.
If the filename begins with `./`, it's resolved as a theme file relative to the current theme file.
Otherwise, the filename is resolved as a theme file in the normal way (relative to the value of the `pdf-themesdir` attribute).

Currently, the base theme is always loaded first.
Then, the files referenced by the extends key are loaded in order.
Finally, the keys in the current file are loaded.
Each time a theme is loaded, the keys are overlaid onto the keys from the previous theme.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

|extends
|String or Array
(default: [])
|extends:
- default
- ./brand-theme.yml
|===

[#keys-role]
=== Role

The keys in the `role` category define custom roles for formatting.
The name of the role is the first subkey level.
The role name may not contain a hyphen or underscore.
The keys under the role are the concrete theming properties.

Here's an example of a role for making text red:

[source,yaml]
----
role:
  red:
    font-color: #ff0000
----

This role can be used as follows:

[source,asciidoc]
----
Error text is shown in [.red]#red#.
----

Currently, custom roles only apply to inline phrases and only support changing the font properties.

The converter provides several predefined roles.
The `big` and `small` roles map the font size to the $base-font-size-large and $base-font-size-small values, respectively.
These two roles can be redefined.
The `underline` and `line-through` roles add the underline and strikethrough decorations, respectively.
These two roles _can't_ be redefined.
The color roles (e.g., `blue`), which you may be familiar with from the HTML converter, are not mapped by default.
You'll need to define these in your theme if you'd like to make use of them when converting to PDF.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-role]*Key Prefix:* <<key-prefix-role,role-<name>{zwsp}>>

|font-color
|<<colors,Color>> +
(default: _inherit_)
|role:
  red:
    font-color: #ff0000

|font-family
|<<fonts,Font family name>> +
(default: Courier)
|role:
  label:
    font-family: M+ 1mn

|font-size
|<<values,Number>> +
(default: _inherit_)
|role:
  large:
    font-size: 12

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|role:
  heavy:
    font-style: bold
|===

[#keys-page]
=== Page

The keys in this category control the size, margins and background of each page (i.e., canvas).
We recommended that you define this category before all other categories.

NOTE: The background of the title page can be styled independently of other pages.
See <<Title Page>> for details.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-page]*Key Prefix:* <<key-prefix-page,page>>

|background-color^[1]^
|<<colors,Color>> +
(default: #ffffff)
|page:
  background-color: #fefefe

|background-image^[2]^
|image macro^[3]^ +
(default: _not set_)
|page:
  background-image: image:page-bg.png[]

|background-image-(recto{vbar}verso)^[2]^
|image macro^[3]^ +
(default: _not set_)
|page:
  background-image:
    recto: image:page-bg-recto.png[]
    verso: image:page-bg-verso.png[]

|initial-zoom
|Fit {vbar} FitH {vbar} FitV +
(default: FitH)
|page:
  initial-zoom: Fit

|layout
|portrait {vbar} landscape +
(default: portrait)
|page:
  layout: landscape

|margin
|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>> +
(default: 36)
|page:
  margin: [0.5in, 0.67in, 1in, 0.67in]

|margin-inner^[4]^
|<<measurement-units,Measurement>> +
(default: 48)
|page:
  margin-inner: 0.75in

|margin-outer^[4]^
|<<measurement-units,Measurement>> +
(default: 24)
|page:
  margin-outer: 0.59in

|size
|https://github.com/prawnpdf/pdf-core/blob/0.6.0/lib/pdf/core/page_geometry.rb#L16-L68[Named size^] {vbar} <<measurement-units,Measurement[width,height]>> +
(default: A4)
|page:
  size: Letter

|numbering-start-at
|title {vbar} toc {vbar} body +
(default: body)
|page:
  numbering-start-at: toc
|===

. To disable the background color for the page, set the value to white (i.e., FFFFFF).
The color keyword `transparent` is not recognized in this context.
. By default, page background images are automatically scaled to fit the bounds of the page (i.e., `fit=contain`) and centered (i.e., `position=center`).
The size of the background image can be controlled using any of the sizing attributes on the image macro (i.e., fit, pdfwidth, scaledwidth, or width).
The position of the background image can be controlled using the `position` attribute.
If the recto (right-hand, odd-numbered pages) or verso (left-hand, even-numbered pages) background is specified, it will be used only for that side.
If you define the keys using the flatten structure (e.g., `page-background-image-recto`), you can also set the default page background image (`page-background-image`), which will then be used as a fallback if a background image isn't specified for a given side.
To disable the background image, use the value `none`.
. Target may be an absolute path or a path relative to the value of the `pdf-themesdir` attribute.
. The margins for `recto` (right-hand, odd-numbered) and `verso` (left-hand, even-numbered) pages are calculated automatically from the margin-inner and margin-outer values.
These margins and used when the value `prepress` is assigned to the `media` document attribute.

[#keys-base]
=== Base

The keys in this category provide generic theme settings and are often referenced throughout the theme file as variables.
We recommended that you define this category after the page category and before all other categories.

NOTE: While it's common to define additional keys in this category (e.g., `base-border-radius`) to keep your theme DRY, we recommend using <<Custom Variables,custom variables>> instead.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-base]*Key Prefix:* <<key-prefix-base,base>>

|align
|<<text-alignments,Text alignment>> +
(default: left)
|base:
  align: justify

|border-color
|<<colors,Color>> +
(default: #eeeeee)
|base:
  border-color: #eeeeee

// border-radius is variable, not an official key
//|border-radius
//|<<values,Number>>
//|base:
//  border-radius: 4

|border-width
|<<values,Number>> +
(default: 0.5)
|base:
  border-width: 0.5

|font-color
|<<colors,Color>> +
(default: #000000)
|base:
  font-color: #333333

|font-family
|<<fonts,Font family name>> +
(default: Helvetica)
|base:
  font-family: Noto Serif

|font-kerning
|normal {vbar} default +
(default: normal)
|base:
  font-kerning: none

|font-size
|<<values,Number>> +
(default: 12)
|base:
  font-size: 10.5

// font-size-large is a variable, not an official key
//|font-size-large
//|<<values,Number>>
//|base:
//  font-size-large: 13

|font-size-min
|<<values,Number>> +
(default: 6)
|base:
  font-size-min: $base-font-size * 0.75

// font-size-small is a variable, not an official key
//|font-size-small
//|<<values,Number>>
//|base:
//  font-size-small: 9

|font-style
|<<font-styles,Font style>> +
(default: normal)
|base:
  font-style: normal

|text-transform^[1]^
|none +
(default: none)
|base:
  text-transform: none

|line-height-length^[2]^
|<<values,Number>> +
(default: _not set_)
|base:
  line-height-length: 12

|line-height^[2]^
|<<values,Number>> +
(default: 1.15)
|base:
  line-height: >
    $base-line-height-length /
    $base-font-size
|===

. The `text-transform` key cannot be set globally.
Therefore, this key should not be used.
The value of `none` is implicit and is documented here for completeness.
. The `line-height-length` is a pseudo property that's local the theme.
It's often used for computing the `base-line-height` from the base font size and the desired line height size.
For instance, if you set `base-line-height-length`, you can use `$base-line-height-length / $base-font-size` to set the value of `base-line-height`.

[#keys-vertical-spacing]
=== Vertical Spacing

The keys in this category control the general spacing between elements where a more specific setting is not designated.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

|vertical-spacing
|<<values,Number>> +
(default: 12)
|vertical-spacing: 10
|===

[#keys-link]
=== Link

The keys in this category are used to style hyperlink text.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-link]*Key Prefix:* <<key-prefix-link,link>>

|font-color
|<<colors,Color>> +
(default: #0000ee)
|link:
  font-color: #428bca

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|link:
  font-family: Roboto

|font-size
|<<values,Number>> +
(default: _inherit_)
|link:
  font-size: 9

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|link:
  font-style: italic

|text-decoration
|none {vbar} underline {vbar} line-through +
(default: none)
|link:
  text-decoration: underline
|===

[#keys-literal]
=== (Inline) Literal

The keys in this category are used for inline monospaced text in prose and table cells.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-literal]*Key Prefix:* <<key-prefix-literal,literal>>

|background-color
|<<colors,Color>> +
(default: _not set_)
|literal:
  background-color: #f5f5f5

|border-color^[1]^
|<<colors,Color>> +
(default: _not set_)
|literal:
  border-color: #cccccc

|border-offset^[2]^
|<<values,Number>> +
(default: 0)
|literal:
  border-offset: 2

|border-radius
|<<values,Number>> +
(default: _not set_)
|literal:
  border-radius: 3

|border-width
|<<values,Number>> +
(default: $base-border-width)
|literal:
  border-width: 0.5

|font-color
|<<colors,Color>> +
(default: _inherit_)
|literal:
  font-color: #b12146

|font-family
|<<fonts,Font family name>> +
(default: Courier)
|literal:
  font-family: M+ 1mn

|font-size
|<<values,Number>> +
(default: _inherit_)
|literal:
  font-size: 12

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|literal:
  font-style: bold
|===
. The border is only used if a border color is specified and the border width is not explicitly set to 0.
The border only works properly if the literal phrase does not have nested formatting.
Otherwise, the border will be inherited, producing a less than desirable result.
. The border offset is the amount that the background and border swells around the text.
It does not affect the distance between the formatted phrase and the phrases that surround it.

[#keys-heading]
=== Heading

The keys in this category control the style of most headings, including part titles, chapter titles, sections titles, the table of contents title and discrete headings.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-heading]*Key Prefix:* <<key-prefix-heading,heading>>

|align
|<<text-alignments,Text alignment>> +
(default: $base-align)
|heading:
  align: center

|font-color
|<<colors,Color>> +
(default: _inherit_)
|heading:
  font-color: #222222

|font-family
|<<fonts,Font family name>> +
(default: $base-font-family)
|heading:
  font-family: Noto Serif

// NOTE: heading-font-size is overridden by h<n>-font-size in base theme
//|font-size
//|<<values,Number>> +
//(default: $base-font-size)
//|heading:
//  font-size: 18

|font-style
|<<font-styles,Font style>> +
(default: bold)
|heading:
  font-style: bold

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|heading:
  text-transform: uppercase

|line-height
|<<values,Number>> +
(default: 1.15)
|heading:
  line-height: 1.2

|margin-top
|<<measurement-units,Measurement>> +
(default: 4)
|heading:
  margin-top: $vertical-spacing * 0.2

|margin-page-top
|<<measurement-units,Measurement>> +
(default: 0)
|heading:
  margin-page-top: $vertical-spacing

|margin-bottom
|<<measurement-units,Measurement>> +
(default: 12)
|heading:
  margin-bottom: 9.6

|min-height-after
|<<measurement-units,Measurement>> +
(default: $base-font-size * $base-line-height * 1.5)
|heading:
  min-height-after: 0.5in

|chapter-break-before
|always {vbar} auto +
(default: always)
|heading:
  chapter:
    break-before: auto

|part-break-before
|always {vbar} auto +
(default: always)
|heading:
  part:
    break-before: auto

|part-break-after
|always {vbar} auto +
(default: auto)
|heading:
  part:
    break-after: always

3+|[#key-prefix-heading-level]*Key Prefix:* <<key-prefix-heading-level,heading-h<n>{zwsp}>>^[1]^

|align
|<<text-alignments,Text alignment>> +
(default: $heading-align)
|heading:
  h2-align: center

|font-color
|<<colors,Color>> +
(default: $heading-font-color)
|heading:
  h2-font-color: [0, 99%, 100%, 0]

|font-family
|<<fonts,Font family name>> +
(default: $heading-font-family)
|heading:
  h4-font-family: Roboto

|font-size^[1]^
|<<values,Number>> +
(default: <1>=24; <2>=18; <3>=16; <4>=14; <5>=12; <6>=10)
|heading:
  h6-font-size: $base-font-size * 1.7

|font-style
|<<font-styles,Font style>> +
(default: $heading-font-style)
|heading:
  h3-font-style: bold_italic

|text-transform
|<<text-transforms,Text transform>> +
(default: $heading-text-transform)
|heading:
  h3-text-transform: lowercase

|margin-top
|<<measurement-units,Measurement>> +
(default: $heading-margin-top)
|heading:
  h2-margin-top: $vertical-spacing * 0.5

|margin-page-top
|<<measurement-units,Measurement>> +
(default: $heading-margin-page-top)
|heading:
  h2-margin-page-top: $vertical-spacing

|margin-bottom
|<<measurement-units,Measurement>> +
(default: $heading-margin-bottom)
|heading:
  h2-margin-bottom: 10
|===

. `<n>` is a number ranging from 1 to 6, representing each of the six heading levels.
. A font size is assigned to each heading level by the base theme.
If you want the font size of a specific level to be inherited, you must assign the value `null` (or `~` for short).

[#keys-title-page]
=== Title Page

The keys in this category control the style of the title page as well as the arrangement and style of the elements on it.

IMPORTANT: The title page is only enabled by default for the book doctype (e.g., `:doctype: book`).
If you want to enable the title page when using a different doctype (such as the article doctype), you must define the `title-page` attribute in the document header (i.e., `:title-page:`).

TIP: The title page can be disabled for the book doctype by setting the `notitle` attribute in the AsciiDoc document header (i.e., `:notitle:`).
(For other doctypes, just don't set the `title-page` attribute).

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-title-page]*Key Prefix:* <<key-prefix-title-page,title-page>>

|align
|<<text-alignments,Text alignment>> +
(default: center)
|title-page:
  align: right

|background-color^[1]^
|<<colors,Color>> +
(default: _inherit_)
|title-page:
  background-color: #eaeaea

|background-image^[2]^
|image macro^[3]^ +
(default: _not set_)
|title-page:
  background-image: image:title.png[]

|font-color
|<<colors,Color>> +
(default: _inherit_)
|title-page:
  font-color: #333333

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|title-page:
  font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: _inherit_)
|title-page:
  font-size: 13

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|title-page:
  font-style: bold

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|title-page:
  text-transform: uppercase

|line-height
|<<values,Number>> +
(default: 1.15)
|title-page:
  line-height: 1

3+|[#key-prefix-title-page-logo]*Key Prefix:* <<key-prefix-title-page-logo,title-page-logo>>

|align
|<<image-alignments,Image alignment>> +
(default: _inherit_)
|title-page:
  logo:
    align: right

|image
|image macro^[3]^ +
(default: _not set_)
|title-page:
  logo:
    image: image:logo.png[pdfwidth=25%]

|top
|Percentage^[4]^ +
(default: 10%)
|title-page:
  logo:
    top: 25%

3+|[#key-prefix-title-page-title]*Key Prefix:* <<key-prefix-title-page-title,title-page-title>>

|font-color
|<<colors,Color>> +
(default: _inherit_)
|title-page:
  title:
    font-color: #999999

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|title-page:
  title:
    font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: 18)
|title-page:
  title:
    font-size: $heading-h1-font-size

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|title-page:
  title:
    font-style: bold

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|title-page:
  title:
    text-transform: uppercase

|line-height
|<<values,Number>> +
(default: $heading-line-height)
|title-page:
  title:
    line-height: 0.9

|top
|Percentage^[3]^ +
(default: 40%)
|title-page:
  title:
    top: 55%

|margin-top
|<<measurement-units,Measurement>> +
(default: 0)
|title-page:
  title:
    margin-top: 13.125

|margin-bottom
|<<measurement-units,Measurement>> +
(default: 0)
|title-page:
  title:
    margin-bottom: 5

3+|[#key-prefix-title-page-subtitle]*Key Prefix:* <<key-prefix-title-page-subtitle,title-page-subtitle>>

|font-color
|<<colors,Color>> +
(default: _inherit_)
|title-page:
  subtitle:
    font-color: #181818

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|title-page:
  subtitle:
    font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: 14)
|title-page:
  subtitle:
    font-size: $heading-h3-font-size

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|title-page:
  subtitle:
    font-style: bold_italic

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|title-page:
  subtitle:
    text-transform: uppercase

|line-height
|<<values,Number>> +
(default: $heading-line-height)
|title-page:
  subtitle:
    line-height: 1

|margin-top
|<<measurement-units,Measurement>> +
(default: 0)
|title-page:
  subtitle:
    margin-top: 13.125

|margin-bottom
|<<measurement-units,Measurement>> +
(default: 0)
|title-page:
  subtitle:
    margin-bottom: 5

3+|[#key-prefix-authors]*Key Prefix:* <<key-prefix-authors,title-page-authors>>

|delimiter
|<<quoted-string,Quoted string>> +
(default: ', ')
|title-page:
  authors:
    delimiter: '; '

|font-color
|<<colors,Color>> +
(default: _inherit_)
|title-page:
  authors:
    font-color: #181818

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|title-page:
  authors:
    font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: _inherit_)
|title-page:
  authors:
    font-size: 13

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|title-page:
  authors:
    font-style: bold_italic

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|title-page:
  authors:
    text-transform: uppercase

|margin-top
|<<measurement-units,Measurement>> +
(default: 12)
|title-page:
  authors:
    margin-top: 13.125

|margin-bottom
|<<measurement-units,Measurement>> +
(default: 0)
|title-page:
  authors:
    margin-bottom: 5

3+|[#key-prefix-revision]*Key Prefix:* <<key-prefix-revision,title-page-revision>>

|delimiter
|<<quoted-string,Quoted string>> +
(default: ', ')
|title-page:
  revision:
    delimiter: ': '

|font-color
|<<colors,Color>> +
(default: _inherit_)
|title-page:
  revision:
    font-color: #181818

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|title-page:
  revision:
    font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: _inherit_)
|title-page:
  revision:
    font-size: $base-font-size-small

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|title-page:
  revision:
    font-style: bold

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|title-page:
  revision:
    text-transform: uppercase

|margin-top
|<<measurement-units,Measurement>> +
(default: 0)
|title-page:
  revision:
    margin-top: 13.125

|margin-bottom
|<<measurement-units,Measurement>> +
(default: 0)
|title-page:
  revision:
    margin-bottom: 5
|===

. To disable the background color for the title page, set the value to white (i.e., FFFFFF).
The color keyword `transparent` is not recognized in this context.
. By default, page background images are automatically scaled to fit the bounds of the page (i.e., `fit=contain`) and centered (i.e., `position=center`).
The size of the background image can be controlled using any of the sizing attributes on the image macro (i.e., fit, pdfwidth, scaledwidth, or width).
The position of the background image can be controlled using the `position` attribute.
. Target may be an absolute path or a path relative to the value of the `pdf-themesdir` attribute.
. Percentage unit can be % (relative to content height) or vh (relative to page height).

[#keys-prose]
=== Prose

The keys in this category control the spacing around paragraphs (paragraph blocks, paragraph content of a block, and other prose content).
Typically, all the margin is placed on the bottom.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-prose]*Key Prefix:* <<key-prefix-prose,prose>>

|margin-top
|<<measurement-units,Measurement>> +
(default: 0)
|prose:
  margin-top: 0

|margin-bottom
|<<measurement-units,Measurement>> +
(default: 12)
|prose:
  margin-bottom: $vertical-spacing

|margin-inner^[1]^
|<<measurement-units,Measurement>> +
(default: $prose-margin-bottom)
|prose:
  margin-inner: 0

|text-indent
|<<measurement-units,Measurement>> +
(default: _not set_)
|prose:
  text-indent: 18
|===

. Controls the margin between adjacent paragraphs.
Useful when using indented paragraphs.

[#keys-block]
=== Block

The keys in this category control the spacing around block elements when a more specific setting is not designated.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-block]*Key Prefix:* <<key-prefix-block,block>>

//|padding
//|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>>
//|block:
//  padding: [12, 15, 12, 15]

|margin-top
|<<measurement-units,Measurement>> +
(default: 0)
|block:
  margin-top: 6

|margin-bottom
|<<measurement-units,Measurement>> +
(default: 12)
|block:
  margin-bottom: 6
|===

Block styles are applied to the following block types:

[cols="3*a",grid=none,frame=none]
|===
|
* admonition
* example
* quote
|
* verse
* sidebar
* image
|
* listing
* literal
* table
|===

[#keys-caption]
=== Caption

The keys in this category control the arrangement and style of block captions.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-caption]*Key Prefix:* <<key-prefix-caption,caption>>

|align
|<<text-alignments,Text alignment>> +
(default: left)
|caption:
  align: left

|font-color
|<<colors,Color>> +
(default: _inherit_)
|caption:
  font-color: #333333

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|caption:
  font-family: M+ 1mn

|font-size
|<<values,Number>> +
(default: _inherit_)
|caption:
  font-size: 11

|font-style
|<<font-styles,Font style>> +
(default: italic)
|caption:
  font-style: italic

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|caption:
  text-transform: uppercase

|margin-inside
|<<measurement-units,Measurement>> +
(default: 4)
|caption:
  margin-inside: 3

|margin-outside
|<<measurement-units,Measurement>> +
(default: 0)
|caption:
  margin-outside: 0
|===

[#keys-code]
=== Code

The keys in this category are used to control the style of literal, listing and source blocks.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-code]*Key Prefix:* <<key-prefix-code,code>>

|background-color
|<<colors,Color>> +
(default: _not set_)
|code:
  background-color: #f5f5f5

|border-color
|<<colors,Color>> +
(default: #eeeeee)
|code:
  border-color: #cccccc

|border-radius
|<<values,Number>> +
(default: _not set_)
|code:
  border-radius: 4

|border-width
|<<values,Number>> +
(default: 0.5)
|code:
  border-width: 0.75

|font-color
|<<colors,Color>> +
(default: _inherit_)
|code:
  font-color: #333333

|font-family
|<<fonts,Font family name>> +
(default: Courier)
|code:
  font-family: M+ 1mn

|font-size
|<<values,Number>> +
(default: 10.8)
|code:
  font-size: 11

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|code:
  font-style: italic

|line-height
|<<values,Number>> +
(default: 1.2)
|code:
  line-height: 1.25

|line-gap^[1]^
|<<values,Number>> +
(default: 0)
|code:
  line-gap: 3.8

|padding
|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>> +
(default: 9)
|code:
  padding: 11

3+|[#key-prefix-code-linenum]*Key Prefix:* <<key-prefix-code-linenum,code-linenum>>^[2]^

|font-color
|<<colors,Color>> +
(default: #999999)
|code:
  linenum-font-color: #ccc
|===
. The line-gap property is used to tune the height of the background color applied to a span of block text highlighted using Rouge.
. The code-linenum category only applies when using Pygments as the source highlighter.
Otherwise, the style is controlled by the source highlighter theme.

[#keys-callout-numbers]
=== Callout Numbers

The keys in this category are used to control the style of callout numbers (i.e., conums) inside verbatim blocks and in callout lists (colists).

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-conum]*Key Prefix:* <<key-prefix-conum,conum>>

|font-color
|<<colors,Color>> +
(default: _inherit_)
|conum:
  font-color: #b12146

|font-family^[1,2]^
|<<fonts,Font family name>> +
(default: _inherit_)
|conum:
  font-family: M+ 1mn

|font-size^[2]^
|<<values,Number>> +
(default: _inherit_)
|conum:
  font-size: $base-font-size

|font-style^[2]^
|<<font-styles,Font style>> +
(default: _inherit_)
|conum:
  font-style: normal

|line-height^[2]^
|<<values,Number>> +
(default: 1.15)
|conum:
  line-height: 4 / 3

|glyphs^[2]^
|circled {vbar} filled {vbar} Unicode String ranges +
(default: circled)
|conum:
  glyphs: \u0031-\u0039
|===

. Currently, the font must contain the circle numbers starting at glyph U+2460.
. font-family, font-size, font-style, and line-height are only used for markers in a colist.
These properties are inherited for conums inside a verbatim block.
. The font must provide the required glyphs.
The glyphs can be specified as a comma-separated list of ranges, where the range values are Unicode numbers (e.g., \u2460).

[#keys-button]
=== Button

The keys in this category apply to a button reference (generated from the inline button macro).

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-button]*Key Prefix:* <<key-prefix-button,button>>

|background-color
|<<colors,Color>> +
(default: _not set_)
|button:
  background-color: #0000ff

|border-color^[1]^
|<<colors,Color>> +
(default: _not set_)
|button:
  border-color: #cccccc

|border-offset^[2]^
|<<values,Number>> +
(default: 0)
|button:
  border-offset: 1.5

|border-radius
|<<values,Number>> +
(default: 0)
|button:
  border-radius: 2

|border-width
|<<values,Number>> +
(default: $base-border-width)
|button:
  border-width: 0.5

|content^[3]^
|<<quoted-string,Quoted string>> +
(default: "%s")
|button:
  content: "[\u2009%s\u2009]"

|font-color
|<<colors,Color>> +
(default: _inherit_)
|button:
  font-color: #ffffff

|font-family
|<<fonts,Font family name>> +
(default: Courier)
|button:
  font-family: M+ 1mn

|font-size
|<<values,Number>> +
(default: _inherit_)
|button:
  font-size: 12

|font-style
|<<font-styles,Font style>> +
(default: bold)
|button:
  font-style: normal
|===
. The border is only used if a border color is specified and the border width is not explicitly set to 0.
. The border offset is the amount that the background and border swells around the text.
It does not affect the distance between the formatted phrase and the phrases that surround it.
. The character sequence `%s` in the content key gets replaced with the button label.

[#keys-key]
=== Key

The keys in this category apply to a key reference (generated from the inline kbd macro).

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-key]*Key Prefix:* <<key-prefix-key,key>>

|background-color
|<<colors,Color>> +
(default: _not set_)
|key:
  background-color: #fafafa

|border-color^[1]^
|<<colors,Color>> +
(default: _not set_)
|key:
  border-color: #cccccc

|border-offset^[2]^
|<<values,Number>> +
(default: 0)
|key:
  border-offset: 1.5

|border-radius
|<<values,Number>> +
(default: 0)
|key:
  border-radius: 2

|border-width
|<<values,Number>> +
(default: $base-border-width)
|key:
  border-width: 0.375

|separator^[3]^
|<<quoted-string,Quoted string>> +
(default: "+")
|key:
  separator: "\u2009+\u2009"

|font-color
|<<colors,Color>> +
(default: _inherit_)
|key:
  font-color: #000

|font-family
|<<fonts,Font family name>> +
(default: Courier)
|key:
  font-family: $base-font-family

|font-size
|<<values,Number>> +
(default: _inherit_)
|key:
  font-size: 10.5

|font-style
|<<font-styles,Font style>> +
(default: italic)
|key:
  font-style: normal
|===
. The border is only used if a border color is specified and the border width is not explicitly set to 0.
. The border offset is the amount that the background and border swells around the text.
It does not affect the distance between the formatted phrase and the phrases that surround it.
. The separator is only used for multi-key sequences.

[#keys-menu]
=== Menu

The keys in this category apply to the menu label (generated from the inline menu macro).

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-menu]*Key Prefix:* <<key-prefix-menu,menu>>

|caret-content
|<<quoted-string,Quoted string>> +
(default: " \u203a ")
|menu:
  caret-content: ' > '
|===

[#keys-blockquote]
=== Blockquote

The keys in this category control the arrangement and style of quote blocks.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-blockquote]*Key Prefix:* <<key-prefix-blockquote,blockquote>>

|border-width^[1]^
|<<values,Number>> +
(default: 4)
|blockquote:
  border-width: 5

|border-color^[1]^
|<<colors,Color>> +
(default: #eeeeee)
|blockquote:
  border-color: #eeeeee

|font-color
|<<colors,Color>> +
(default: _inherit_)
|blockquote:
  font-color: #333333

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|blockquote:
  font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: _inherit_)
|blockquote:
  font-size: 13

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|blockquote:
  font-style: bold

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|blockquote:
  text-transform: uppercase

|padding
|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>> +
(default: [6, 12, -6, 14])
|blockquote:
  padding: [5, 10, -5, 12]

3+|[#key-prefix-blockquote-cite]*Key Prefix:* <<key-prefix-blockquote-cite,blockquote-cite>>

|font-size
|<<values,Number>> +
(default: _inherit_)
|blockquote:
  cite:
    font-size: 9

|font-color
|<<colors,Color>> +
(default: _inherit_)
|blockquote:
  cite:
    font-color: #999999

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|blockquote:
  cite:
    font-family: Noto Serif

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|blockquote:
  cite:
    font-style: bold

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|blockquote:
  cite:
    text-transform: uppercase
|===

. Only applies to the left side.

[#keys-sidebar]
=== Sidebar

The keys in this category control the arrangement and style of sidebar blocks.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-sidebar]*Key Prefix:* <<key-prefix-sidebar,sidebar>>

|background-color
|<<colors,Color>> +
(default: #eeeeee)
|sidebar:
  background-color: #eeeeee

|border-color
|<<colors,Color>> +
(default: _not set_)
|sidebar:
  border-color: #ffffff

|border-radius
|<<values,Number>> +
(default: _not set_)
|sidebar:
  border-radius: 4

|border-width
|<<values,Number>> +
(default: _not set_)
|sidebar:
  border-width: 0.5

|font-color
|<<colors,Color>> +
(default: _inherit_)
|sidebar:
  font-color: #262626

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|sidebar:
  font-family: M+ 1p

|font-size
|<<values,Number>> +
(default: _inherit_)
|sidebar:
  font-size: 13

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|sidebar:
  font-style: italic

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|sidebar:
  text-transform: uppercase

|padding
|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>> +
(default: [12, 12, 0, 12])
|sidebar:
  padding: [12, 15, 0, 15]

3+|[#key-prefix-sidebar-title]*Key Prefix:* <<key-prefix-sidebar-title,sidebar-title>>

|align
|<<text-alignments,Text alignment>> +
(default: center)
|sidebar:
  title:
    align: center

|font-color
|<<colors,Color>> +
(default: _inherit_)
|sidebar:
  title:
    font-color: #333333

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|sidebar:
  title:
    font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: _inherit_)
|sidebar:
  title:
    font-size: 13

|font-style
|<<font-styles,Font style>> +
(default: bold)
|sidebar:
  title:
    font-style: bold

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|sidebar:
  title:
    text-transform: uppercase
|===

[#keys-example]
=== Example

The keys in this category control the arrangement and style of example blocks.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-example]*Key Prefix:* <<key-prefix-example,example>>

|background-color
|<<colors,Color>> +
(default: #ffffff)
|example:
  background-color: #fffef7

|border-color
|<<colors,Color>> +
(default: #eeeeee)
|example:
  border-color: #eeeeee

|border-radius
|<<values,Number>> +
(default: _not set_)
|example:
  border-radius: 4

|border-width
|<<values,Number>> +
(default: 0.5)
|example:
  border-width: 0.75

|font-color
|<<colors,Color>> +
(default: _inherit_)
|example:
  font-color: #262626

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|example:
  font-family: M+ 1p

|font-size
|<<values,Number>> +
(default: _inherit_)
|example:
  font-size: 13

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|example:
  font-style: italic

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|example:
  text-transform: uppercase

|padding
|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>> +
(default: [12, 12, 0, 12])
|example:
  padding: [15, 15, 0, 15]
|===

[#keys-admonition]
=== Admonition

The keys in this category control the arrangement and style of admonition blocks and the icon used for each admonition type.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-admonition]*Key Prefix:* <<key-prefix-admonition,admonition>>

|column-rule-color
|<<colors,Color>> +
(default: #eeeeee)
|admonition:
  column-rule-color: #aa0000

|column-rule-style
|solid {vbar} double {vbar} dashed {vbar} dotted +
(default: solid)
|admonition:
  column-rule-style: double

|column-rule-width
|<<values,Number>> +
(default: 0.5)
|admonition:
  column-rule-width: 0.5

|font-color
|<<colors,Color>> +
(default: _inherit_)
|admonition:
  font-color: #999999

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|admonition:
  font-family: Noto Sans

|font-size
|<<values,Number>> +
(default: _inherit_)
|admonition:
  font-size: $base-font-size-large

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|admonition:
  font-style: italic

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|admonition:
  text-transform: none

|padding
|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>> +
(default: [0, 12, 0, 12])
|admonition:
  padding: [0, 12, 0, 12]

3+|[#key-prefix-admonition-label]*Key Prefix:* <<key-prefix-admonition-label,admonition-label>>

|align
|<<text-alignments,Text alignment>> +
(default: center)
|admonition:
  label:
    align: center

|min-width
|<<measurement-units,Measurement>> +
(default: _not set_)
|admonition:
  label:
    min-width: 48

|padding^[1]^
|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>> +
(default: $admonition-padding)
|admonition:
  padding: [0, 12, 0, 12]

|vertical-align
|top {vbar} middle {vbar} bottom +
(default: middle)
|admonition:
  label:
    vertical-align: top

3+|*Key Prefix:* admonition-label, admonition-label-<name>^[2]^

|font-color
|<<colors,Color>> +
(default: _inherit_)
|admonition:
  label:
    font-color: #262626

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|admonition:
  label:
    font-family: M+ 1p

|font-size
|<<values,Number>> +
(default: _inherit_)
|admonition:
  label:
    font-size: 12

|font-style
|<<font-styles,Font style>> +
(default: bold)
|admonition:
  label:
    font-style: bold_italic

|text-transform
|<<text-transforms,Text transform>> +
(default: uppercase)
|admonition:
  label:
    text-transform: lowercase

3+|[#key-prefix-admonition-icon]*Key Prefix:* <<key-prefix-admonition-icon,admonition-icon-<name>{zwsp}>>^[2]^

|name
|<icon set>-<icon name>^[3]^ +
(default: _not set_)
|admonition:
  icon:
    tip:
      name: fas-fire

|stroke-color
|<<colors,Color>> +
(default: caution=#bf3400; important=#bf0000; note=#19407c; tip=#111111; warning=#bf6900)
|admonition:
  icon:
    important:
      stroke-color: ff0000

|size
|<<values,Number>> +
(default: 24)
|admonition:
  icon:
    note:
      size: 24
|===

. The top and bottom padding values are ignored on admonition-label-padding.
. `<name>` can be `note`, `tip`, `warning`, `important`, or `caution`.
All icon types must be grouped under a single `icons` category.
In other words, _do not_ declare the `icons` category multiple times.
The subkeys in the icon category cannot be flattened (e.g., `tip-name: far-lightbulb` is not valid syntax).
. Required.
See the `.yml` files in the https://github.com/jessedoyle/prawn-icon/tree/master/data/fonts[prawn-icon repository] for a list of valid icon names.
The prefix (e.g., `fas-`) determines which font set to use.

[#keys-image]
=== Image

The keys in this category control the arrangement of block images.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-image]*Key Prefix:* <<key-prefix-image,image>>

|align
|<<image-alignments,Image alignment>> +
(default: left)
|image:
  align: left

|width^[1]^
|<<measurement-units,Measurement>> +
(default: _not set_)
|image:
  width: 100%

|border-color^[2]^
|<<colors,Color>> +
(default: _not set_)
|image:
  border-color: #cccccc

|border-radius
|<<values,Number>> +
(default: _not set_)
|image:
  border-radius: 2

|border-width^[2]^
|<<values,Number>> +
(default: _not set_)
|image:
  border-width: 0.5

|border-fit^[3]^
|content {vbar} auto
(default: content)
|image:
  border-fit: auto
|===

. Only applies to block images.
If specified, this value takes precedence over the value of the `width` attribute on the image macro, but not over the value of the `pdfwidth` attribute.
. The border is only used if a border color is specified, the border width is specified, the border width is greater than 0, and the `noborder` role is not present.
The border is drawn above the image on the inside of the box reserved for the image.
. The value `auto` means the border should expand to fit the width of the container (i.e., full width) instead of the image.

[#keys-svg]
=== SVG

The keys in this category control the SVG integration.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-image]*Key Prefix:* <<key-prefix-svg,svg>>

|fallback_font_family^[1]^
|<<fonts,Font family name>> +
(default: $base-font-family)
|svg:
  fallback_font_family: Times-Roman
|===
. The fallback font family is only used when the font family in the SVG does not map to a known font name from the font catalog.

[#keys-lead]
=== Lead

The keys in this category control the styling of lead paragraphs.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-lead]*Key Prefix:* <<key-prefix-lead,lead>>

|font-color
|<<colors,Color>> +
(default: _inherit_)
|lead:
  font-color: #262626

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|lead:
  font-family: M+ 1p

|font-size
|<<values,Number>> +
(default: 13.5)
|lead:
  font-size: 13

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|lead:
  font-style: bold

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|lead:
  text-transform: uppercase

|line-height
|<<values,Number>> +
(default: 1.4)
|lead:
  line-height: 1.4
|===

[#keys-abstract]
=== Abstract

The keys in this category control the arrangement and style of the abstract.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-abstract]*Key Prefix:* <<key-prefix-abstract,abstract>>

|font-color
|<<colors,Color>> +
(default: $base-font-color)
|abstract:
  font-color: #5c6266

|font-size
|<<values,Number>> +
(default: 13.5)
|abstract:
  font-size: 13

|font-style
|<<font-styles,Font style>> +
(default: $base-font-style)
|abstract:
  font-style: italic

|text-transform
|<<text-transforms,Text transform>> +
(default: $base-text-transform)
|abstract:
  text-transform: uppercase

|line-height
|<<values,Number>> +
(default: 1.4)
|abstract:
  line-height: 1.4

|padding
|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>> +
(default: 0)
|abstract:
  padding: [0, 12, 0, 12]

3+|[#key-prefix-abstract-title]*Key Prefix:* <<key-prefix-abstract-title,abstract-title>>

|align
|<<text-alignments,Text alignment>> +
(default: center)
|abstract:
  title:
    align: center

|font-color
|<<colors,Color>> +
(default: $base-font-color)
|abstract:
  title:
    font-color: #333333

|font-family
|<<fonts,Font family name>> +
(default: $base-font-family)
|abstract:
  title:
    font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: $base-font-size)
|abstract:
  title:
    font-size: 13

|font-style
|<<font-styles,Font style>> +
(default: bold)
|abstract:
  title:
    font-style: bold

|text-transform
|<<text-transforms,Text transform>> +
(default: $base-text-transform)
|abstract:
  title:
    text-transform: uppercase
|===

[#keys-thematic-break]
=== Thematic Break

The keys in this category control the style of thematic breaks (aka horizontal rules).

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-thematic-break]*Key Prefix:* <<key-prefix-thematic-break,thematic-break>>

|border-color
|<<colors,Color>> +
(default: #eeeeee)
|thematic-break:
  border-color: #eeeeee

|border-style
|solid {vbar} double {vbar} dashed {vbar} dotted +
(default: solid)
|thematic-break:
  border-style: dashed

|border-width
|<<measurement-units,Measurement>> +
(default: 0.5)
|thematic-break:
  border-width: 0.5

|margin-top
|<<measurement-units,Measurement>> +
(default: 0)
|thematic-break:
  margin-top: 6

|margin-bottom
|<<measurement-units,Measurement>> +
(default: $vertical-spacing)
|thematic-break:
  margin-bottom: 18
|===

[#keys-description-list]
=== Description List

The keys in this category control the arrangement and style of definition list items (terms and descriptions).

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-description-list]*Key Prefix:* <<key-prefix-description-list,description-list>>

|term-font-style
|<<font-styles,Font style>> +
(default: bold)
|description-list:
  term-font-style: italic

|term-spacing
|<<measurement-units,Measurement>> +
(default: 4)
|description-list:
  term-spacing: 5

|description-indent
|<<values,Number>> +
(default: 30)
|description-list:
  description-indent: 15
|===

[#keys-outline-list]
=== Outline List

The keys in this category control the arrangement and style of outline list items.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-outline-list]*Key Prefix:* <<key-prefix-outline-list,outline-list>>

|indent
|<<measurement-units,Measurement>> +
(default: 30)
|outline-list:
  indent: 40

|item-spacing
|<<measurement-units,Measurement>> +
(default: 6)
|outline-list:
  item-spacing: 4

|marker-font-color^[1]^
|<<colors,Color>> +
(default: _inherit_)
|outline-list:
  marker-font-color: #3c763d

|text-align^[2]^
|<<text-alignments,Text alignment>> +
(default: $base-align)
|outline-list:
  text-align: left
|===

. Controls the color of the bullet glyph that marks items in unordered lists and the number for items in ordered lists.
. Controls the alignment of the list text only, not nested content (blocks or lists).

[#keys-ulist]
=== Unordered List

The keys in this category control the arrangement and style of unordered list items.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-ulist-marker]*Key Prefix:* <<key-prefix-ulist-marker,ulist-marker>>

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|ulist:
  marker:
    font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: _inherit_)
|ulist:
  marker:
    font-size: 9

|font-color
|<<colors,Color>> +
(default: $outline-list-marker-font-color)
|ulist:
  marker:
    font-color: #cccccc

|line-height
|<<values,Number>> +
(default: $base-line-height)
|ulist:
  marker:
    line-height: 1.5
|===

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-ulist-marker-type]*Key Prefix:* <<key-prefix-ulist-marker-type,ulist-marker-<type>{zwsp}>>^[1]^

|content
|<<quoted-string,Quoted string>>
|ulist:
  marker:
    disc:
      content: "\uf140"

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|ulist:
  marker:
    disc:
      font-family: fas

|font-size
|<<values,Number>> +
(default: _inherit_)
|ulist:
  marker:
    disc:
      font-size: 9

|font-color
|<<colors,Color>> +
(default: _inherit_)
|ulist:
  marker:
    disc:
      font-color: #ff0000

|line-height
|<<values,Number>> +
(default: _inherit_)
|ulist:
  marker:
    disc:
      line-height: 2
|===

. <type> is one of disc, square, circle, checked, unchecked

[#keys-table]
=== Table

The keys in this category control the arrangement and style of tables and table cells.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-table]*Key Prefix:* <<key-prefix-table,table>>

|background-color
|<<colors,Color>> +
(default: transparent)
|table:
  background-color: #ffffff

|border-color
|<<colors,Color>> +
(default: #000000)
|table:
  border-color: #dddddd

|border-style
|solid {vbar} dashed {vbar} dotted +
(default: solid)
|table:
  border-style: solid

|border-width
|<<values,Number>> +
(default: 0.5)
|table:
  border-width: 0.5

|caption-side
|top {vbar} bottom +
(default: top)
|table:
  caption-side: bottom

|caption-max-width
|fit-content {vbar} none +
(default: fit-content)
|table:
  caption-max-width: none

|font-color
|<<colors,Color>> +
(default: _inherit_)
|table:
  font-color: #333333

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|table:
  font-family: Helvetica

|font-size
|<<values,Number>> +
(default: _inherit_)
|table:
  font-size: 9.5

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|table:
  font-style: italic

|grid-color
|<<colors,Color>> +
(default: $table-border-color)
|table:
  grid-color: #eeeeee

|grid-style
|solid {vbar} dashed {vbar} dotted +
(default: solid)
|table:
  grid-style: dashed

|grid-width
|<<values,Number>> +
(default: $table-border-width)
|table:
  grid-width: 0.5

3+|[#key-prefix-table-head]*Key Prefix:* <<key-prefix-table-head,table-head>>

//|align
//|<<text-alignments,Text alignment>> +
//(default: _inherit_)
//|table:
//  head:
//    align: center

|background-color
|<<colors,Color>> +
(default: $table-background-color)
|table:
  head:
    background-color: #f0f0f0

|border-bottom-color
|<<colors,Color>> +
(default: $table-border-color)
|table:
  head:
    border-bottom-color: #dddddd

|border-bottom-style
|solid {vbar} dashed {vbar} dotted +
(default: solid)
|table:
  head:
    border-bottom-style: dashed

|border-bottom-width
|<<values,Number>> +
(default: 1.25)
|table:
  head:
    border-bottom-width: 1

|font-color
|<<colors,Color>> +
(default: $table-font-color)
|table:
  head:
    font-color: #333333

|font-family
|<<fonts,Font family name>> +
(default: $table-font-family)
|table:
  head:
    font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: $table-font-size)
|table:
  head:
    font-size: 10

|font-style
|<<font-styles,Font style>> +
(default: bold)
|table:
  head:
    font-style: normal

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|table:
  head:
    text-transform: uppercase

3+|[#key-prefix-table-body]*Key Prefix:* <<key-prefix-table-body,table-body>>

|background-color
|<<colors,Color>> +
(default: $table-background-color)
|table:
  body:
    background-color: #fdfdfd

|stripe-background-color^[1]^
|<<colors,Color>> +
(default: #eeeeee)
|table:
  body:
    stripe-background-color: #efefef

3+|[#key-prefix-table-foot]*Key Prefix:* <<key-prefix-table-foot,table-foot>>

|background-color
|<<colors,Color>> +
(default: $table-background-color)
|table:
  foot:
    background-color: #f0f0f0

|font-color
|<<colors,Color>> +
(default: $table-font-color)
|table:
  foot:
    font-color: #333333

|font-family
|<<fonts,Font family name>> +
(default: $table-font-family)
|table:
  foot:
    font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: $table-font-size)
|table:
  foot:
    font-size: 10

|font-style
|<<font-styles,Font style>> +
(default: normal)
|table:
  foot:
    font-style: italic

3+|[#key-prefix-table-cell]*Key Prefix:* <<key-prefix-table-cell,table-cell>>

|padding
|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>> +
(default: 2)
|table:
  cell:
    padding: 3

3+|[#key-prefix-table-header-cell]*Key Prefix:* <<key-prefix-table-header-cell,table-header-cell>>

//|align
//|<<text-alignments,Text alignment>> +
//(default: $table-head-align)
//|table:
//  header-cell:
//    align: center

|background-color
|<<colors,Color>> +
(default: $table-head-background-color)
|table:
  header-cell:
    background-color: #f0f0f0

|font-color
|<<colors,Color>> +
(default: $table-head-font-color)
|table:
  header-cell:
    font-color: #1a1a1a

|font-family
|<<fonts,Font family name>> +
(default: $table-head-font-family)
|table:
  header-cell:
    font-family: Noto Sans

|font-size
|<<values,Number>> +
(default: $table-head-font-size)
|table:
  header-cell:
    font-size: 12

|font-style
|<<font-styles,Font style>> +
(default: $table-head-font-style)
|table:
  header-cell:
    font-style: italic

|text-transform
|<<text-transforms,Text transform>> +
(default: $table-head-text-transform)
|table:
  header-cell:
    text-transform: uppercase
|===
. This key only controls the color that is used for stripes.
The appearance of stripes is controlled using the `stripes` table attribute, the `table-stripes` document attribute (since Asciidoctor 2), or the `stripes` document attribute (prior to Asciidoctor 2).
Permitted attribute values are even, odd, all, and none.
Prior to Asciidoctor 2, even rows are shaded by default (e.g., `stripes=even`).
Since Asciidoctor 2, table stripes are not enabled by default (e.g., `stripes=none`).

[#keys-footnotes]
=== Footnotes

The keys in this catagory control the style the list of footnotes at the end of the chapter (book) or document (otherwise).
If the `footnotes-title` attribute is specified, it is styled as a block caption.
The styling of the links is controlled by the global link styles.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-footnotes]*Key Prefix:* <<key-prefix-footnotes,footnotes>>

|font-color
|<<colors,Color>> +
(default: $base-font-color)
|footnotes:
  font-color: #cccccc

|font-size
|<<values,Number>> +
(default: 9)
|footnotes:
  font-size: 8

|font-style
|<<font-styles,Font style>> +
(default: $base-font-style)
|footnotes:
  font-style: italic

|item-spacing
|<<measurement-units,Measurement>> +
(default: 3)
|footnotes:
  item-spacing: 5

|margin-top
|<<measurement-units,Measurement>> +
(default: 0)
|footnotes:
  margin-top: 10

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|footnotes:
  text-transform: lowercase
|===

[#keys-table-of-contents]
=== Table of Contents (TOC)

The keys in this category control the arrangement and style of the table of contents.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-toc]*Key Prefix:* <<key-prefix-toc,toc>>

|font-color
|<<colors,Color>> +
(default: _inherit_)
|toc:
  font-color: #333333

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|toc:
  font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: _inherit_)
|toc:
  font-size: 9

|font-style
|<<font-styles,Font style>> +
// QUESTION why is the default not inherited?
(default: normal)
|toc:
  font-style: bold

|text-decoration
|none {vbar} underline +
(default: none)
|toc:
  text-decoration: underline

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|toc:
  text-transform: uppercase

|line-height
|<<values,Number>> +
(default: 1.4)
|toc:
  line-height: 1.5

|indent
|<<measurement-units,Measurement>> +
(default: 15)
|toc:
  indent: 20

|margin-top
|<<measurement-units,Measurement>> +
(default: 0)
|toc:
  margin-top: 0

3+|[#key-prefix-toc-level]*Key Prefix:* <<key-prefix-toc-level,toc-h<n>{zwsp}>>^[1]^

|font-color
|<<colors,Color>> +
(default: _inherit_)
|toc:
  h3-font-color: #999999

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|toc:
  font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: _inherit_)
|toc:
  font-size: 9

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|toc:
  font-style: italic

|text-decoration
|none {vbar} underline +
(default: _inherit_)
|toc:
  text-decoration: none

|text-transform
|<<text-transforms,Text transform>> +
(default: _inherit_)
|toc:
  text-transform: uppercase

3+|[#key-prefix-toc-title]*Key Prefix:* <<key-prefix-toc-title,toc-title>>

|align
|<<text-alignments,Text alignment>> +
(default: $heading-h2-align)
|toc:
  title:
    align: right

|font-color
|<<colors,Color>> +
(default: $heading-h2-font-color)
|toc:
  title:
    font-color: #aa0000

|font-family
|<<fonts,Font family name>> +
(default: $heading-h2-font-family)
|toc:
  title:
    font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: $heading-h2-font-size)
|toc:
  title:
    font-size: 18

|font-style
|<<font-styles,Font style>> +
(default: $heading-h2-font-style)
|toc:
  title:
    font-style: bold_italic

|text-transform
|<<text-transforms,Text transform>> +
(default: $heading-h2-text-transform)
|sidebar:
  title:
    text-transform: uppercase

3+|[#key-prefix-toc-dot-leader]*Key Prefix:* <<key-prefix-toc-dot-leader,toc-dot-leader>>

|content
|<<quoted-string,Quoted string>> +
(default: '. ')
|toc:
  dot-leader:
    content: ". "

|font-color^[2]^
|<<colors,Color>> +
(default: _inherit_)
|toc:
  dot-leader:
    font-color: #999999

|font-style^[2]^
|<<font-styles,Font style>> +
(default: normal)
|toc:
  dot-leader:
    font-style: bold

|levels^[3]^
|all {vbar} none {vbar} Integers (space-separated) +
(default: all)
|toc:
  dot-leader:
    levels: 2 3
|===

. `<n>` is a number ranging from 1 to 6, representing each of the six heading levels.
. The dot leader inherits all font properties except `font-style` from the root `toc` category.
. 0-based levels (e.g., part = 0, chapter = 1).
Dot leaders are only shown for the specified levels.
If value is not specified, dot leaders are shown for all levels.

[#keys-running-content]
=== Running Content (Header & Footer)

The keys in this category control the arrangement and style of running header and footer content.
Please note that the running content will _not_ be used unless a) the periphery (header or footer) is configured and b) the height key for the periphery is assigned a value.

CAUTION: If the height of the running content periphery is larger than the page margin, the running content will cover the main content.
To avoid this problem, reduce the height of the running content periphery or make the page margin on that side larger.

[cols="3,4,5l"]
|===
|Key |Value Type |Example

3+|[#key-prefix-running-content]*Key Prefix:* <<key-prefix-running-content,running-content>>

|start-at
|title {vbar} toc {vbar} body +
(default: body)
|running-content:
  start-at: toc

3+|[#key-prefix-header]*Key Prefix:* <<key-prefix-header,header>>

|background-color^[1]^
|<<colors,Color>> +
(default: _not set_)
|header:
  background-color: #eeeeee

|border-color
|<<colors,Color>> +
(default: _not set_)
|header:
  border-color: #dddddd

|border-style
|solid {vbar} double {vbar} dashed {vbar} dotted +
(default: solid)
|header:
  border-style: dashed

|border-width
|<<measurement-units,Measurement>> +
(default: $base-border-width)
|header:
  border-width: 0.25

|font-color
|<<colors,Color>> +
(default: _inherit_)
|header:
  font-color: #333333

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|header:
  font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: _inherit_)
|header:
  font-size: 9

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|header:
  font-style: italic

|height^[2]^
|<<measurement-units,Measurement>> +
(default: _not set_)
|header:
  height: 0.75in

|line-height
|<<values,Number>> +
(default: $base-line-height)
|header:
  line-height: 1.2

|padding^[3]^
|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>> +
(default: 0)
|header:
  padding: [0, 3, 0, 3]

|image-vertical-align
|top {vbar} middle {vbar} bottom {vbar} <<measurement-units,Measurement>> +
(default: _not set_)
|header:
  image-vertical-align: 4

|sectlevels
|Integer +
(default: 2)
|header:
  sectlevels: 3

|text-transform
|<<text-transforms,Text transform>> +
(default: none)
|header:
  text-transform: uppercase

|title-style
|document {vbar} toc {vbar} basic +
(default: document)
|header:
  title-style: toc

|vertical-align
|top {vbar} middle {vbar} bottom +
(default: middle)
|header:
  vertical-align: center

|<side>-columns^[4]^
|Column specs triple +
(default: _not set_)
|header:
  recto:
    columns: <25% =50% >25%

|<side>-<position>-content^[4,5]^
|<<quoted-string,Quoted string>> +
(default: '\{page-number}')
|header:
  recto:
    left:
      content: '\{page-number}'

3+|[#key-prefix-footer]*Key Prefix:* <<key-prefix-footer,footer>>

|background-color^[1]^
|<<colors,Color>> +
(default: _not set_)
|footer:
  background-color: #eeeeee

|border-color
|<<colors,Color>> +
(default: _not set_)
|footer:
  border-color: #dddddd

|border-style
|solid {vbar} double {vbar} dashed {vbar} dotted +
(default: solid)
|footer:
  border-style: dashed

|border-width
|<<measurement-units,Measurement>> +
(default: $base-border-width)
|footer:
  border-width: 0.25

|font-color
|<<colors,Color>> +
(default: _inherit_)
|footer:
  font-color: #333333

|font-family
|<<fonts,Font family name>> +
(default: _inherit_)
|footer:
  font-family: Noto Serif

|font-size
|<<values,Number>> +
(default: _inherit_)
|footer:
  font-size: 9

|font-style
|<<font-styles,Font style>> +
(default: _inherit_)
|footer:
  font-style: italic

|height^[2]^
|<<measurement-units,Measurement>> +
(default: _not set_)
|footer:
  height: 0.75in

|line-height
|<<values,Number>> +
(default: $base-line-height)
|footer:
  line-height: 1.2

|padding^[3]^
|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>> +
(default: 0)
|footer:
  padding: [0, 3, 0, 3]

|image-vertical-align
|top {vbar} middle {vbar} bottom {vbar} <<measurement-units,Measurement>> +
(default: _not set_)
|footer:
  image-vertical-align: 4

|sectlevels
|Integer +
(default: 2)
|footer:
  sectlevels: 3

|text-transform
|<<text-transforms,Text transform>> +
(default: none)
|footer:
  text-transform: uppercase

|title-style
|document {vbar} toc {vbar} basic +
(default: document)
|footer:
  title-style: toc

|vertical-align
|top {vbar} middle {vbar} bottom +
(default: middle)
|footer:
  vertical-align: top

|<side>-columns^[4]^
|Column specs triple +
(default: _not set_)
|footer:
  verso:
    columns: <50% =0% <50%

|<side>-<position>-content^[4,5]^
|<<quoted-string,Quoted string>> +
(default: '\{page-number}')
|footer:
  verso:
    center:
      content: '\{page-number}'
|===
. The background color spans the width of the page, as does the border when a background color is specified.
. *If the height is not set, the running content at this periphery is disabled.*
. If the side padding is negative, the content will bleed into the margin of the page.
. `<side>` can be `recto` (right-hand, odd-numbered pages) or `verso` (left-hand, even-numbered pages).
Where the page sides fall in relation to the physical or printed page number is controlled using the `pdf-folio-placement` attribute (except when `media=prepress`, which implies `physical`).
. `<position>` can be `left`, `center` or `right`.

IMPORTANT: If you don't specify a height for either the header or footer key, it effectively disables the content at that periphery.

If you define running header and footer content in your theme (including the height), you can still disable this content per document by setting the `noheader` and `nofooter` attributes in the AsciiDoc document header, respectively.

If content is not specified for the running footer, the page number (i.e., `\{page-number}`) is shown on the left on verso pages and the right on recto pages.
You can disable this behavior by defining the attribute `nofooter` in the AsciiDoc document header or by defining the key `footer-<side>-content: none` in the theme.

TIP: Although not listed in the table above, you can control the font settings (font-family, font-size, font-color, font-style, text-transform) that get applied to the running content in each column position for each page side (e.g., `footer-<side>-<position>-font-color`).
For example, you can set the font color used for the right-hand column on recto pages by setting `footer-recto-right-font-color: 6CC644`.

==== Attribute References

You can use _any_ attribute defined in your AsciiDoc document (such as `doctitle`) in the content of the running header and footer.
In addition, the following attributes are also available when defining the content keys in the footer:

* page-count
* page-number
* document-title
* document-subtitle
* part-title
* chapter-title
* section-title
* section-or-chapter-title

You can also built-in AsciiDoc text replacements like `+(C)+`, numeric character references like `+&#169;+` and inline formatting (e.g., bold, italic, monospace).

Here's an example that shows how attributes and replacements can be used in the running footer:

[source,yaml]
----
header:
  height: 0.75in
  line-height: 1
  recto:
    center:
      content: '(C) ACME -- v{revnumber}, {docdate}'
  verso:
    center:
      content: $header-recto-center-content
footer:
  height: 0.75in
  line-height: 1
  recto:
    right:
      content: '{section-or-chapter-title} | *{page-number}*'
  verso:
    left:
      content: '*{page-number}* | {chapter-title}'
----

You can split the content value across multiple lines using YAML's multiline string syntax.
In this case, the single quotes around the string are not necessary.
To force a hard line break in the output, add `{sp}+` to the end of the line in normal AsciiDoc fashion.

[source,yaml]
----
footer:
  height: 0.75in
  line-height: 1.2
  recto:
    right:
      content: |
        Section Title - Page Number +
        {section-or-chapter-title} - {page-number}
  verso:
    left:
      content: |
        Page Number - Chapter Title +
        {page-number} - {chapter-title}
----

TIP: You can use most AsciiDoc inline formatting in the values of these keys.
For instance, to make the text bold, surround it in asterisks (as shown above).
One exception to this rule are inline images, which are described in the next section.

==== Images

You can add an image to the running header or footer using the AsciiDoc inline image syntax.
The image target is resolved relative to the value of the `pdf-themesdir` attribute.
If the image macro is the whole value for a column position, you can use the `position` and `fit` attributes to align and scale it relative to the column box.
Otherwise, the image is treated like a normal inline image, for which you can only adjust the width.

Here's an example of how to use an image in the running header (which also applies for the footer).

[source,yaml,subs=attributes+]
----
header:
  height: 0.75in
  image-vertical-align: 2 {conum-guard-yaml} <1>
  recto:
    center:
      content: image:footer-logo.png[width=80]
  verso:
    center:
      content: $header-recto-center-content
----
<1> You can use the `footer-vertical-align` attribute to slighly nudge the image up or down.

CAUTION: By default, the image must fit in the allotted space for the running header or footer.
Otherwise, you will run into layout issues.
Adjust the width attribute accordingly using the `pdfwidth` attribute.
Alternatively, you can set the `fit` attribute to `scale-down` (e.g., `fit=scale-down`) to reduce the image size to fit in the available space or `contain` (i.e., `fit=contain`) to scale the image (up or down) to fit the available space.

== Applying Your Theme

After creating a theme, you'll need to tell Asciidoctor PDF where to find it.
This is done using AsciiDoc attributes.

There are three AsciiDoc attributes that tell Asciidoctor PDF how to locate and apply your theme.

pdf-theme (or pdf-style):: The name of the YAML theme file to load.
If the name ends with `.yml`, it's assumed to be the complete name of a file and is resolved relative to `pdf-themesdir`, if specified, otherwise the current directory.
Otherwise, `-theme.yml` is appended to the name to make the file name (i.e., `<name>-theme.yml`) and is resolved relative to `pdf-themesdir`, if specified, otherwise the built-in themes dir.

pdf-themesdir (or pdf-stylesdir):: The directory where the theme file is located.
_Specifying an absolute path is recommended._
+
If you use images in your theme, image paths are resolved relative to this directory.
If `pdf-theme` ends with `.yml`, and `pdf-themesdir` is not specified, then `pdf-themesdir` defaults to the directory of the path specified by `pdf-theme`.

pdf-fontsdir:: The directory or directories where the fonts used by your theme, if any, are located.
Multiple entries must be separated by a semi-colon.
_Specifying an absolute path is recommended._

Let's assume that you've put your theme files inside a directory named `resources` with the following layout:

....
document.adoc
resources/
  themes/
    basic-theme.yml
  fonts/
    roboto-normal.ttf
    roboto-italic.ttf
    roboto-bold.ttf
    roboto-bold_italic.ttf
....

Here's how you'd load your theme when calling Asciidoctor PDF:

 $ asciidoctor-pdf -a pdf-themesdir=resources/themes -a pdf-theme=basic -a pdf-fontsdir=resources/fonts

If all goes well, Asciidoctor PDF should run without an error or warning.

NOTE: You only need to specify the `pdf-fontsdir` if you're using custom fonts in your theme.

You can skip setting the `pdf-themesdir` attribute and just pass the absolute path of your theme file to the `pdf-theme` attribute.

 $ asciidoctor-pdf -a pdf-theme=resources/themes/basic-theme.yml -a pdf-fontsdir=resources/fonts

However, in this case, image paths in your theme won't be resolved properly.

Paths are resolved relative to the current directory.
However, in the future, this may change so that paths are resolved relative to the base directory (typically the document's directory).
Therefore, it's recommend that you specify absolute paths for now to future-proof your configuration.

 $ asciidoctor-pdf -a pdf-themesdir=/path/to/resources/themes -a pdf-theme=basic -a pdf-fontsdir=/path/to/resources/fonts

As usual, you can also use build tools like Maven and Gradle to build a themed PDF.
The only thing you need to add to an existing build is the attributes mentioned above.

* https://github.com/asciidoctor/asciidoctor-maven-examples/tree/master/asciidoctor-pdf-with-theme-example[Maven Example]
* https://github.com/asciidoctor/asciidoctor-gradle-examples/tree/master/asciidoc-to-pdf-with-theme-example[Gradle Example]

== Theme-Related Document Attributes

There are various settings in the theme you control using document attributes.
These settings override equivalent keys defined in the theme file, where applicable.

[cols="2,3,6l"]
|===
|Attribute |Value Type |Example

|autofit-option
|flag (default: _not set_)
|:autofit-option:

|chapter-label
|string (default: Chapter)
|:chapter-label: Chapitre

|<face>-cover-image^[1]^
|path^[2]^ {vbar} image macro^[3]^ +
(format can be image or PDF)
|:front-cover-image: image:front-cover.pdf[]

|media
|screen {vbar} print {vbar} prepress
|:media: prepress

|outlinelevels^[10]^
|Integer {vbar} Integer:Integer (default: same as _toclevels_)
|:outlinelevels: 2

|page-background-image^[4]^
|path^[2]^ {vbar} image macro^[3]^
|:page-background-image: image:bg.jpg[]

|page-background-image-(recto{vbar}verso)^[4]^
|path^[2]^ {vbar} image macro^[3]^
|:page-background-image-recto: image:bg-recto.jpg[]

|pagenums^[5]^
|flag (default: _set_)
|:pagenums:

|pdf-page-layout
|portrait {vbar} landscape
|:pdf-page-layout: landscape

|pdf-page-margin
|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>>
|:pdf-page-margin: [1in, 0.5in]

|pdf-page-size
|https://github.com/prawnpdf/pdf-core/blob/0.6.0/lib/pdf/core/page_geometry.rb#L16-L68[Named size^] {vbar} <<measurement-units,Measurement[width, height]>>
|:pdf-page-size: 6in x 9in

|pdf-folio-placement
|virtual {vbar} virtual-inverted {vbar} physical {vbar} physical-inverted
|:pdf-folio-placement: physical

|pdf-version
|1.3 {vbar} 1.4 {vbar} 1.5 {vbar} 1.6 {vbar} 1.7 (default: 1.4)
|:pdf-version: 1.7

|pdfmark^[6]^
|flag (default: _not set_)
|:pdfmark:

|text-align^[7]^
|<<text-alignments,Text alignment>>
|:text-align: left

|title-logo-image
|path^[2]^ {vbar} image macro^[3]^
|:title-logo-image: image:logo.png[top=25%, align=center, pdfwidth=0.5in]

|title-page^[8]^
|flag (default: _not set_)
|:title-page:

|title-page-background-image
|path^[2]^ {vbar} image macro^[3]^
|:title-page-background-image: image:title-bg.jpg[]

|toc-max-pagenum-digits^[9]^
|Integer (default: 3)
|:toc-max-pagenum-digits: 4
|===

. `<face>` can be `front` or `back`.
. The path is resolved relative to base_dir.
. The target of the image macro is resolved relative to `imagesdir`.
If the image macro syntax is not used, the value is resolved relative to the base directory, which defaults to the document directory.
. By default, page background images are automatically scaled to fit the bounds of the page (i.e., `fit=contain`) and centered (i.e., `position=center`).
The size of the background image can be controlled using any of the sizing attributes on the image macro (i.e., fit, pdfwidth, scaledwidth, or width).
The position of the background image can be controlled using the `position` attribute.
If the recto (right-hand, odd-numbered pages) or verso (left-hand, even-numbered pages) background is specified, it will be used only for that side.
If a background image isn't specified for a side, the converter will use the default page background image (`page-background-image`), if specified.
To disable the background image for a side, use the value `none`.
. Controls whether the `page-number` attribute is accessible to the running header and footer content specified in the theme file.
Use the `noheader` and `nofooter` attributes to disable the running header and footer, respectively, from the document.
. Enables generation of the http://milan.kupcevic.net/ghostscript-ps-pdf/#marks[pdfmark] file, which contains metadata that is fed to Ghostscript when optimizing the PDF file.
. _(Experimental)_ The `text-align` document attribute is intended as a simple way to toggle text justification.
The value of this attribute overrides the `base-align` key set by the theme.
For more fine-grained control, you should customize using the theme.
. The title page is only enabled by default for the book doctype.
To force the title page to be used for other doctypes, set the `title-page` attribute in the document header.
. If the TOC overlaps the first page of content, increase this number.
. The second number in the value of `outlinelevels` is the number of levels of the outline to expand (e.g., `3:1`).
If the second number is not present, all levels are expanded.

== Publishing Mode

Asciidoctor PDF provides the following features to assist with publishing:

* Double-sided (mirror) page margins
* Automatic facing pages

These features are activated when you set the `media` attribute to `prepress` in the header of your AsciiDoc document or from the CLI or API.
The following sections describe the behaviors that this setting activates.

=== Double-Sided Page Margins

The page margins for the recto (right-hand, odd-numbered) and verso (left-hand, even-numbered) pages are automatically calculated by replacing the side page margins with the values of the `page-margin-inner` and `page-margin-outer` keys.

For example, let's assume you've defined the following settings in your theme:

[source,yaml]
----
page:
  margin: [0.5in, 0.67in, 0.67in, 0.67in]
  margin-inner: 0.75in
  margin-outer: 0.59in
----

The page margins for the recto and verso pages will be resolved as follows:

recto page margin:: [0.5in, *0.59in*, 0.67in, *0.75in*]
verso page margin:: [0.5in, *0.75in*, 0.67in, *0.59in*]

The page margins alternate between recto and verso.
The first page in the document is a recto page.

=== Automatic Facing Pages

When converting the book doctype using the prepress media setting, a blank page will be inserted when necessary to ensure the following elements start on a recto page:

* Title page
* Table of contents
* First page of body
* Parts and chapters

Other "`facing`" pages may be added in the future.

It's possible to disable the automatic facing feature for a given part or chapter.
This can be done by adding the nonfacing option to the section node.
When the nonfacing option is present, the part or chapter title will be placed on the following page.

[source,asciidoc]
----
[%nonfacing]
= Minor Chapter

content
----

For documents that use the article doctype, Asciidoctor PDF incorrectly places the document title and table of contents on their own pages.
This can result in the page numbering and the page facing to be out of sync.
As a workaround, Asciidoctor PDF inserts a blank page, if necessary, to ensure the first page of body content is a recto-facing page.

You can check on the status of this defect by following https://github.com/asciidoctor/asciidoctor-pdf/issues/95[issue #95].

== Source Highlighting Theme

You can define and apply your own source highlighting theme to source blocks when using Rouge as the source highlighter.
This section explains how.

A custom theme for Rouge is defined using a Ruby class.
Start by creating a Ruby source file to define your theme.
Name the file according to the name of your theme and put the file in a folder of your choice (e.g., [.path]_rouge_themes/custom.rb_).
The name of the Ruby class doesn't matter, though it's customary to name it according to the name of the theme as well.

.rouge_themes/custom.rb
[source,ruby]
----
require 'rouge' unless defined? ::Rouge.version

module Rouge; module Themes
  class Custom < CSSTheme
    name 'custom'

    style Comment,           fg: '#008800', italic: true
    style Error,             fg: '#a61717', bg: '#e3d2d2'
    style Str,               fg: '#0000ff'
    style Str::Char,         fg: '#800080'
    style Num,               fg: '#0000ff'
    style Keyword,           fg: '#000080', bold: true
    style Operator::Word,    bold: true
    style Name::Tag,         fg: '#000080', bold: true
    style Name::Attribute,   fg: '#ff0000'
    style Generic::Deleted,  fg: '#000000', bg: '#ffdddd', inline_block: true, extend: true
    style Generic::Inserted, fg: '#000000', bg: '#ddffdd', inline_block: true, extend: true
    style Text, {}
  end
end; end
----

Each style declaration accepts the following properties:

* `fg` - sets the foreground (text) color
* `bg` - sets the background color
* `bold` - change the font weight to bold
* `italic` - change the font style to italic
* `underline` - add an underline to the text
* `inline_block` - fill the background color to the height of the line (Asciidoctor PDF only)
* `extend` - extend the background color to the end of the line for a line-oriented match (Asciidoctor PDF only)

Colors are defined using hexidecimal format (e.g., #ff0000 for red).

Use the `Text` token to set the background color of the source block and the default text color.

The complete list of tokens can be found in the https://github.com/jneen/rouge/blob/master/lib/rouge/token.rb[token.rb] file from Rouge.
Refer to the https://github.com/jneen/rouge/tree/master/lib/rouge/themes[bundled themes] to find more examples.

Once you've defined your theme, you need to enable it use it using the `rouge-style` document attribute, which you specify in the document header or via the Asciidoctor CLI or API.

[source,asciidoc]
----
:source-highlighter: rouge
:rouge-style: custom
----

Finally, you need to active your theme by requiring the theme file when you invoke Asciidoctor.

 $ asciidoctor -r ./rouge_themes/custom.rb sample.adoc

You should now see that the source code is highlighted to your liking.
For more information about source highlighting with Rouge, refer to the http://rouge.jneen.net/[Rouge project page].

////
== Resources for Extending Asciidoctor PDF

* http://www.sitepoint.com/hackable-pdf-typesetting-in-ruby-with-prawn[Hackable PDF typesetting in Ruby with Prawn]
////

[appendix]
== Preparing a Custom Font

Any TTF font can be used with Prawn--and hence Asciidoctor PDF--without modifications (unless, of course, it's corrupt or contains errors).
However, you may discover that kerning is disabled and certain required glyphs are missing (or replaced with boxes).
To address these problems, you need to prepare the font using a font program such as {url-fontforge}[FontForge].

=== Validate the Font

Before using the font, you may want to check that the font is valid.
To do so, create the following script, which will verify that the TTF font is free from errors.

.validate-font.rb
[source,ruby]
----
require 'ttfunk'
require 'ttfunk/subset_collection'

ttf_subsets = TTFunk::SubsetCollection.new TTFunk::File.open ARGV[0]
(0...(ttf_subsets.instance_variable_get :@subsets).size).each {|idx| ttf_subsets[idx].encode }
----

Run the script on your font as follows:

 $ ruby validate-font.rb path/to/font.ttf

If this script fails, the font will not work with Asciidoctor PDF.
To repair it, open the font in FontForge and resave it using menu:File[Generate Fonts...,Generate].
Dismiss any warning dialogs.

Resaving the font in FontForge will usually resolve any errors in the font.
(If not, you may need to find another font, or at least another copy of it).

=== Modifying the Font

To ready your font for use with Asciidoctor PDF, you'll need to modify it using a font program.
We recommend using {url-fontforge}[FontForge].
But don't let this scare you off.
FontForge essentially works like a vector-drawing tool, in which each character is a separate canvas.
You can find a crash course in how to use the program on the FontForge project site.

Here are the modifications you need to apply to a custom font for it to work best with Asciidoctor PDF:

* Convert the font to TTF (only required if the font is not already a TTF, such as an OTF or TTC).
* Add the glyphs for the required characters if missing from the font (optional if using a fallback font).
* Subset the font to exclude unused characters to reduce the file size (optional).
* Save the file using the old-style kern table to activate kerning.

NOTE: Technically, subsetting the font (i.e., removing glyphs) is not required since Prawn only embeds the characters from the font used in the document (i.e., it automatically subsets the font).
However, if you plan to commit the font to a repository, subsetting helps keep the file size down.

Most fonts do not provide glyphs for all the Unicode character ranges (i.e., scripts).
(A glyph is the corresponding vector image for a Unicode character).
In fact, many fonts only include glyphs for Latin (Basic, Supplement, and Extended) and a few other scripts (e.g., Cyrillic, Greek).
That means certain glyphs Asciidoctor PDF relies on may be missing from the font.

Below are the non-Latin characters (identified by Unicode code point) on which Asciidoctor PDF relies that are often missing from fonts.
Unless you're using a fallback font that fills in the missing glyphs, you need to ensure these glyphs are present in your font (and add them if not).

* \u00a0 - no-break space
* \ufeff - zero width no-break space
* \u200b - zero width space (used for line break hints)
* \u000a - line feed character (zero width)
* \u2009 - thin spaced (used in the button UI element)
* \u202f - narrow no-break space (used in the keybinding UI element)
* \u2011 - non-breaking hyphen
* \u2022 - disc (used for first-level unordered list level)
* \u25e6 - circle (used for second-level unordered list level)
* \u25aa - square (used for third-level unordered list level)
* \u2611 - ballot box checked (used for checked list item)
* \u2610 - ballot box unchecked (used for unchecked list item)
* \u2014 - em-dash (used in quote attribute)
* \u203a - single right-pointing quotation mark (used in the menu UI element)
* \u25ba - right pointer (used for media play icon when icon fonts are disabled)
* .notdef - used as the default glyph when a requested character is missing from the font (usually a box)

NOTE: If the .notdef glyph is non-empty (i.e., contains splines), it will be used as the default glyph when the document requests a character that is missing from the font.
Unlike other glyphs, the .notdef glyph is referenced by name only.
It does not have a designated Unicode code point.

If you're preparing a font for use in verbatim blocks (e.g., a listing block), you'll also need this range of characters:

* \u2460 to \u2468 - circled numbers

One way to get these glyphs is to steal them from another font (or from another character in the same font).
To do so, open the other font in FontForge, select the character, press kbd:[Ctrl,c], switch back to your font, select the character again, and press kbd:[Ctrl,v].
You may need to scale the glyph so it fits properly in the art box.

IMPORTANT: If you're copying a non-visible character, be sure to set the width to 0 using menu:Metrics[Set Width...], enter 0 into *Set Width To*, then click btn:[OK].

When you're done, save the font with the old-style kern table enabled.
To do so, select menu:File[Generate Fonts...], click btn:[Options], and make sure only the following options are selected (equivalent to the flags 0x90 + 0x08):

* [x] OpenType
 ** [x] Old style 'kern'

Then click btn:[Generate] to generate and save the font.

Your font file is now ready to be used with Asciidoctor PDF.

=== Scripting the Font Modifications

Performing all this font modification manually can be tedious (not to mention hard to reproduce).
Fortunately, FontForge provides a {url-fontforge-scripting}[scripting interface], which you can use to automate the process.

In fact, that's what we use to prepare the fonts that are bundled with Asciidoctor PDF.
You can find that FontForge script, the Bash script that calls it, and the Docker image in which it is run in the https://github.com/asciidoctor/asciidoctor-pdf/tree/master/scripts[scripts directory] of this project.
You can use that script as a starting point or reference for your own font preparation / modification script.