anchor.diff:  
   * keep or drop base_ prefix in theme? I think we should keep it because it provides context elsewhere in the document (e.g. $base_font_size vs $font_size)
   
  -== Notes
  -
  -* "section title" is the semantic element; "heading" is the structural element
  -
   == Resources
   
   * https://code.google.com/p/origami-pdf/[Origami PDF: A PDF inspection library]
  
positive.code: * be mindful that layout_prose adds margin to bottom of content by default (important when working in a bounding box)
  * ttfunk does not support ligatures (e.g., fi -> ﬁ); we could do this manually in post_replacements
  
  == API notes
  
  * if we set the vposition to a numeric value, it skips the overrun check that happens internally
  
  == Potential Optimizations
  
  
negative.code: * inline tabs should be replaced in layout_prose (etc) when normalize is enabled
  
  * use treetop to parse and evaluate theme file
  * make source code highlighting theme configurable (should be now, but has problems with conums); still?
  * use or don't use pad method? check performance
  
  == Documentation
  