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.
fit-content
up to the max size, but several people wanted more time to review before resolving (Github issue #1732).::before/after
after ::slotted()
but not opening it to general stacking of elements.