Merge remote-tracking branch 'acheetham/FLUID-4323-demo' into demo

* acheetham/FLUID-4323-demo:
  FLUID-4323: More changes for high-contrast.
  FLUID-4323: Changes for high-contrast.
  FLUID-4323: Clean-up of HTML and improvements to semantics of markup.
FLUID-4323: Remove any asides from the article; reposition TOC