This is a page from the Cascading Style Sheets Working Group Blog. Some other places to find information are the “current work” page, the www-style mailing list, the Future of CSS syndicator, and the issue list on Github.
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.
:drop(active|valid|invalid)
(write-in candidate with best argument).
[rel=next,prev,up]
in attribute selectors. No conclusions yet.
outline
properties. Two use cases conflict: focus outlines (original intended use case), and fake “borders”.