= Asciidoctor PDF Theming
:navtitle: Theming

Asciidoctor PDF comes with a built-in theming system and a default theme.
The theming system is used to control the layout and styling of a PDF file generated from AsciiDoc by Asciidoctor PDF.
You can use the default theme for your PDFs as it is, extend the default theme to change or add styles, or create and apply a custom theme.

== Theme configuration and language

The Asciidoctor PDF theming system is driven by a YAML configuration file.
The Asciidoctor PDF theme language is described using https://en.wikipedia.org/wiki/YAML[YAML] and incorporates many _concepts_ from CSS and SASS, such as selectors, properties, and inheritance.
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.*

== Theme capabilities

The theme can generally influence PDF settings, page numbering, font properties, background and borders, character selections, spacings, and running content.
It has limited influence over the layout of elements on the page.
If your theming requirements demand more than what this theming system can accommodate, you can xref:extend:index.adoc[extend the converter] to gain more control over the layout and style.

//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.
//To learn how the theming system works and how to create and apply custom themes, refer to the <<docs/theming-guide.adoc#,Asciidoctor PDF Theming Guide>>.
You can use the built-in theme files, which you can find in the [.path]_data/themes_ directory, as examples.

If you've enabled a source highlighter, you can control the style (aka theme) it applies to source blocks using the `coderay-style`, `pygments-style`, and `rouge-style` attributes, respectively.
For example, to configure Rouge to use the built-in monokai theme, run Asciidoctor PDF as follows:

 $ asciidoctor-pdf -a rouge-style=monokai basic-example.adoc

It's possible to develop your own theme for Rouge.
Refer to xref:source-highlighting-theme.adoc[] for details.