anchor.diff:  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.
   
  +IMPORTANT: In order for a third-party font to work properly with Prawn (and hence Asciidoctor PDF), several modifications are required.
  +See <<Preparing a Custom Font>> to learn how to prepare your font for use with Asciidoctor PDF.
  +
  +==== Selecting Your Font
  +
   To start, find the TTF file collection for the font you want to use.
  -A collection typically consists of all four font styles:
  +A collection typically consists of four font styles:
   
   * normal
   * italic
  
positive.code:       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
  
  
negative.code: 
  CAUTION: You must declare all four variants.
  If you're missing the font file for one of the variants, configure it to use the same font file as the normal variant.
  
  You can add any number of fonts to the catalog.
  Each font must be assigned a unique key, as shown here:
  