anchor.diff:    line_height: 1.2
   
   |padding
  -|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>>
  +|<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>> +
  +(default: 0)
   |footer:
     padding: [0, 3, 0, 3]
   
   |image_vertical_align
  -|top {vbar} middle {vbar} bottom {vbar} <<measurement-units,Measurement>>
  +|top {vbar} middle {vbar} bottom {vbar} <<measurement-units,Measurement>> +
  +(default: _not set_)
   |footer:
     image_vertical_align: 4
   
   |vertical_align
  -|top {vbar} middle {vbar} bottom
  +|top {vbar} middle {vbar} bottom +
  +(default: middle)
   |footer:
     vertical_align: top
   
  -|<side>_columns^[2]^
  +|<side>_columns^[3]^
   |Column specs triple +
   (default: _not set_)
   |footer:
     verso:
       columns: <50% =0% <50%
   
  -|<side>_<position>_content^[2,3]^
  +|<side>_<position>_content^[3,4]^
   |Quoted string
   |footer:
     verso:
       center:
         content: '\{page-number}'
   |===
  -
   . The background color spans the width of the page, as does the border when a background color is specified.
  +. If the height is not set, the running content on this periphery is disabled.
   . `<side>` can be `recto` (right-hand, odd-numbered pages) or `verso` (left-hand, even-numbered pages).
   . `<position>` can be `left`, `center` or `right`.
   
  
positive.code:   line_height: 1.2
  
  |padding
  |<<measurement-units,Measurement>> {vbar} <<measurement-units,Measurement[top,right,bottom,left]>>
  |header:
    padding: [0, 3, 0, 3]
  
  |image_vertical_align
  |top {vbar} middle {vbar} bottom {vbar} <<measurement-units,Measurement>>
  |header:
    image_vertical_align: 4
  
  |vertical_align
  |top {vbar} middle {vbar} bottom
  |header:
    vertical_align: center
  
  |<side>_columns^[2]^
  |Column specs triple +
  (default: _not set_)
  |header:
    recto:
      columns: <25% =50% >25%
  
  |<side>_<position>_content^[2,3]^
  |Quoted string
  |header:
    recto:
  
negative.code:   border_style: dashed
  
  |border_width
  |<<measurement-units,Measurement>> +
  (default: $base_border_width)
  |header:
    border_width: 0.25
  
  |font_color
  |<<colors,Color>> +
  (default: _inherit_)
  |header:
    font_color: #333333
  
  |font_family
  |<<fonts,Font family name>> +
  (default: _inherit_)
  |header:
    font_family: Noto Serif
  
  |font_size
  |<<values,Number>> +
  (default: _inherit_)
  |header:
    font_size: 9
  
  |font_style
  |<<font-styles,Font style>> +
  (default: _inherit_)
  |header:
    font_style: italic
  
  |height^[2]^
  |<<measurement-units,Measurement>> +
  (default: _not set_)
  |header:
    height: 0.75in
  
  