anchor.diff:  |===
   
   . Page background images are automatically scaled to fit within the bounds of the page.
  -+
  -NOTE: Page backgrounds do not currently work when using AsciidoctorJ PDF.
  -This limitation is due to a bug in Prawn 1.3.1.
  -The limitation will remain until AsciidoctorJ PDF upgrades to Prawn 2.x (an upgrade that is waiting on AsciidoctorJ to migrate to JRuby 9000).
  -For more details, see http://discuss.asciidoctor.org/Asciidoctor-YAML-style-file-for-PDF-and-maven-td3849.html[this thread].
   . Target may be an absolute path or a path relative to the value of the `pdf-stylesdir` attribute.
   . Percentage unit can be % (relative to content height) or vh (relative to page height).
   
  
positive.code: . The target of the image macro is resolved relative to `imagesdir`.
  If the image macro syntax is not used, the value is resolved relative to the base directory, which defaults to the document directory.
  . Page background images are automatically scaled to fit within the bounds of the page.
  +
  NOTE: Page backgrounds do not currently work when using AsciidoctorJ PDF.
  This limitation is due to a bug in Prawn 1.3.1.
  The limitation will remain until AsciidoctorJ PDF upgrades to Prawn 2.x (an upgrade that is waiting on AsciidoctorJ to migrate to JRuby 9000).
  For more details, see http://discuss.asciidoctor.org/Asciidoctor-YAML-style-file-for-PDF-and-maven-td3849.html[this thread].
  . Controls whether the `page-number` attribute is accessible to the running header and footer content specified in the theme file.
  Use the `noheader` and `nofooter` attributes to disable the running header and footer, respectively, from the document.
  . Enables generation of the http://milan.kupcevic.net/ghostscript-ps-pdf/#marks[pdfmark] file, which contains metadata that is fed to Ghostscript when optimizing the PDF file.
  
negative.code: |===
  
  . Page background images are automatically scaled to fit within the bounds of the page.
  . Target may be an absolute path or a path relative to the value of the `pdf-stylesdir` 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.
  