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.
about:invalid as the fallback url in attr().
calc() white space rules; they are required around + and -, and optional around / and *.
order to something more specific so it doesn’t imply that non-visual orders (e.g. tab order or speech order) are affected.