anchor.diff:  
   You can split the content value across multiple lines using YAML's multiline string syntax.
   In this case, the single quotes around the string are not necessary.
  -To force a hard line break in the output, add [x-]+{space}{plus}+ to the end of the line in normal AsciiDoc fashion.
  +To force a hard line break in the output, add `{sp}+` to the end of the line in normal AsciiDoc fashion.
   
   [source,yaml]
   ----
  
positive.code: 
  TIP: The running header and footer can be disabled from the document by setting the `noheader` and the `nofooter` attributes, respectively, in the document header.
  
  NOTE: If content is not specified for the running footer, the page number (i.e., `+{page-number}+`) will be shown on the left side on verso pages and the right side on recto pages.
  
  NOTE: The background color spans the width of the page.
  When a background color is specified, the border also spans the width of the page.
  
negative.code: 
  ////
  Topics remaining to document:
  * document which attributes can be set in document (pdf-page-size, front-cover-image, back-cover-image, etc) (issue #428)
  * line height and line height length (and what that all means)
  * title page layout / title page images (logo & background)
  * document that unicode escape sequences can be used inside double-quoted strings
  ////
  
  [.lead]
  The theming system in Asciidoctor PDF is used to control the layout and styling of the PDF file Asciidoctor PDF generates from AsciiDoc.
  This document describes how the theming system works, how to define a custom theme in YAML and how to activate the theme when running Asciidoctor PDF.
  
  IMPORTANT: If you're using a custom theme, you're expected to override some of keys described in the sections below, in particular fonts.
  If you don't define your own fonts, the built-in PDF fonts will be used.
  
  toc::[]
  
  