anchor.diff:    numbering-start-at: toc
   |===
   
  -. By default, page background images are automatically scaled to fit the bounds of the page (i.e., `fit=contain`).
  -The size of the background can be controlled using any of the sizing attributes on the image macro (i.e., fit, pdfwidth, scaledwidth, or width).
  +. To disable the background color for the page, set the value to white (i.e., FFFFFF).
  +The color keyword `transparent` is not recognized in this context.
  +. By default, page background images are automatically scaled to fit the bounds of the page (i.e., `fit=contain`) and centered (i.e., `position=center`).
  +The size of the background image can be controlled using any of the sizing attributes on the image macro (i.e., fit, pdfwidth, scaledwidth, or width).
  +The position of the background image can be controlled using the `position` attribute.
   If the recto (right-hand, odd-numbered pages) or verso (left-hand, even-numbered pages) background is specified, it will be used only for that side.
  -If you flatten out the keys (e.g., `page-background-recto`), you can also set the default page background image (`page-background`), which will then be used as a fallback if a background image isn't specified for a side.
  -To disable the background for a side, use the value `none`.
  +If you define the keys using the flatten structure (e.g., `page-background-image-recto`), you can also set the default page background image (`page-background-image`), which will then be used as a fallback if a background image isn't specified for a given side.
  +To disable the background image, use the value `none`.
   . Target may be an absolute path or a path relative to the value of the `pdf-themesdir` attribute.
   . The margins for `recto` (right-hand, odd-numbered) and `verso` (left-hand, even-numbered) pages are calculated automatically from the margin-inner and margin-outer values.
   These margins and used when the value `prepress` is assigned to the `media` document attribute.
  
positive.code: |page:
    background-color: #fefefe
  
  |background-image^[1]^
  |image macro^[2]^ +
  (default: _not set_)
  |page:
    background-image: image:page-bg.png[]
  
  |background-image-(recto{vbar}verso)^[1]^
  |image macro^[2]^ +
  (default: _not set_)
  |page:
    background-image:
  
negative.code:     align: right
  
  |image
  |image macro^[3]^ +
  (default: _not set_)
  |title-page:
    logo:
      image: image:logo.png[pdfwidth=25%]
  
  |top
  |Percentage^[4]^ +
  (default: 10%)
  |title-page:
    logo:
  