anchor.diff:  
   A theme (or style) 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 and color values.
  +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.
  
positive.code: 
  ==== RGB
  
  An RGB array value must be three numbers between 0 and 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].
  
negative.code: = Asciidoctor PDF Theming Guide
  Dan Allen <https://github.com/mojavelinux>
  :toc: macro
  :icons: font
  :idprefix:
  :idseparator: -
  