Cascading style sheets have been a good vector for cross site scripting (XSS) bugs lately. Especially as social networking sites move to allowing users more control over their profiles and UI's.

Keeping this in mind, I need to study up on some of the specs:

CSS 2.1

CSS grammar tokenization and lexical parsing model at http://www.w3.org/TR/CSS21/grammar.html.

The official CSS 2.1 specification: Cascading Style Sheets Level 2 Revision 1 (CSS 2.1) Specification
http://www.w3.org/TR/CSS21/

Escaping characters allowed in the CSS 2.1
http://www.w3.org/TR/REC-CSS2/syndata.html.

CSS 2.1 test cases at http://www.w3.org/Style/CSS/Test/CSS2.1/20061011/

Appendix F. Full property table
http://www.w3.org/TR/CSS21/propidx.html