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.
::grammar-error and ::spelling-error in the Pseudo-Elements draftp::selection inherit the style into the spec.::value and ::choices in the near future from implementors, however the group will wait on a formal write-up for ::placeholder before deciding on if ::value and ::choices should be moved to Pseudo-Elements from CSS3 UI.