anchor.diff:  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.
  +Required keys are provided by the *base* theme.
   Therefore, you only have to declare keys that you want to override.
   
   [#keys-page]
  
positive.code:   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).
  
negative.code: All the available keys are documented in <<Keys>>.
  The converter uses the information from the theme map to help construct the PDF.
  
  
  [WARNING]
  ====
  If you start a new theme form scratch, be sure to provide a TrueType font familly for all base text sections (`base`, `literal`, `code`). Base theme only use built-in AFM fonts and some glyphs like callout numbers will be missing.
  ====
  
  [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.
  