TSS

 TSS  is Twitter Style Sheets or Text Style Sheets, a compressed form of CSS applicable to short bits of text, suitable for storing in very small fields like 512 bytes.

Open source CASSIS implementation: http://xent.com/tss.js

Live UI: http://xent.com/rtf (requires JS for the "live" part :)
 * try picking from the presets to see sample "TSS" code, as well as HTML as a result of applying it to sample text. (no need to sign-in to Twitter)

Posts

 * 2010-06-02: http://readwrite.com/2010/06/02/tweeting_in_color_from_the_annotations_hackfest/
 * 2010-06-20: https://gigaom.com/2010/06/20/twitter-annotations-are-coming-what-do-they-mean-for-twitter-and-the-web/
 * 2017-01-13: http://tantek.com/2017/013/t1/csswg-compression-2010-tss