anchor.diff:  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`).
  +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) use relative paths in the theme file and include `GEM_FONT_DIR` in the value of the `pdf-fontsdir` attribute separated by the location of your custom fonts using a semi-colon (e.g., `"path/to/your/fonts;GEM_FONTS_DIR"`).
   
   === Custom Fonts
   
  
positive.code: 
   $ 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.
  
negative.code: 
  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.
  To reference a file inside a JAR file on the classpath, prefix with the path with `uri:classloader:` (AsciidoctorJ only).
  _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:
  