Single line comments using //

[SINE]

Single Line Comments aren't colored properly, they should be treated the same way as any actual CSS parser handles them (everything after them to be treated as commented out).

[benogle]

Single line comments are /* comment here */ in CSS. See http://stackoverflow.com/questions/12298890/is-it-bad-practice-to-comment-out-single-lines-of-css-with

[SINE]

// is known as a next construct comment in CSS.
You may be right in it not being documented by W3C, but please consider this article by Atkins Jr., member of the CSS Working Group:
http://www.xanthir.com/b4U10

It does work, even without being publically endorsed.