Ability to change background and font colours

Light colours are tiring, but a system-wide dark colour scheme (like Solarized Dark) doesn't play well with some apps and in some situations. So ability to change the bacrground and font colours would be a fine convenience.

Edit: Not sure if it's relevant, but might give you some ideas: A Qt markdown app (Qarkdown – http://hasseg.org/hgweb/qarkdown/summary and http://hasseg.org/peg-markdown-highlight/) gives four colour/syntax highlighting scheme options: Dark Solarized, Dark Solarized subtle, Light Solarized, Light Solarized subtle.

Edit: Yet another (markdown) highlighter approach using json (offers a stripped down ReText as a sample app):

https://github.com/rupeshk/MarkdownHighlighter