anchor.diff:  |link:
     font_color: #428bca
   
  -|font_family
  -|<<fonts,Font family name>>
  -|link:
  -  font_family: Roboto
  -
  -|font_size
  -|<<values,Number>>
  -|link:
  -  font_size: 9
  -
  -|font_style
  -|normal {vbar} italic {vbar} bold {vbar} bold_italic
  -|link:
  -  font_style: normal
  +// font_family, font_size and font_style not yet implemented
  +//|font_family
  +//|<<fonts,Font family name>>
  +//|link:
  +//  font_family: Roboto
  +//
  +//|font_size
  +//|<<values,Number>>
  +//|link:
  +//  font_size: 9
  +//
  +//|font_style
  +//|normal {vbar} italic {vbar} bold {vbar} bold_italic
  +//|link:
  +//  font_style: normal
   |===
   
   === Literal inline
  
positive.code: 
  === Heading
  
  The keys in this category control the style of headings, including titles for parts, chapters, sections and the table of contents, as well as discrete headings.
  
  [cols="3,4,5l"]
  |===
  
negative.code:     $base_line_height_length /
      $base_font_size
  
  // border_radius is not an official key
  //|border_radius
  //|<<values,Number>>
  //|base:
  //  border_radius: 4
  
  |border_width
  |<<values,Number>> +
  