Do you want to know how the CSS WG works? Fantasai has written about:csswg, An Inside View of the CSS Working Group at W3C.
The CSS Working Group has published a Candidate Recommendation (and call for implementations) of the CSS Conditional Rules Module Level 3. This module describes the @media and @supports rules and associated APIs. It extends CSS level 2 by allowing nesting of certain at-rules inside ‘@media’ and adding the ‘@supports’ rule for conditional processing.
The working group is interested in feedback from authors and implementations, contributions to the test suite, and feedback on the tests in the test suite.
Changes since the last Working Draft are listed in the Changes section.