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.
@keyframe rules cascade.
pseudoElement on animation events. Mark at-risk. Revisit in a few months if it’s a web-compat problem.
width feature. Expect LC in a few weeks.
column-gap, not to column-width (use column-count for that, it’s better).