anchor.diff:  
   |heading_margin_top
   |<<measurement-units,measurement>>
  -|margin_top: $vertical_rhythm * 0.2
  +|margin_top: $vertical_spacing * 0.2
   
   |heading_margin_bottom
   |<<measurement-units,measurement>>
  
positive.code: |vertical_spacing: 10
  |===
  
  //NOTE: Vertical and horizontal rhythm are used for vertical and horizontal spacing, respectively, when there a specific theme key is not defined for a certain purpose.
  //These keys predated the CSS-style theme system and are planned to be phased out.
  
  === Link
  
  [cols="3,3,5m"]
  
negative.code: * font_style
  * line_height (currently some exceptions)
  * text_transform (only for headings)
  * margin_bottom (falls back to $vertical_spacing)
  
  .Heading Inheritance
  ****
  