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.
Resolved: Proposal to normalize language strings associated with the document to 3066 before matching against :lang() accepted.
Resolved: Attribute substring matches against empty string (specifically,
[attr*=""]) considered invalid. Note: This resolution was later retracted.
Resolved: Spec needs to clarify that
::first-letter applies to content including generated content.
Resolved: Selectors must define that pseudo-class names are case-insensitive within the ASCII range (i.e. [a-z] and [A-Z] match each other, but match nothing outside that range).
Resolved: absolutely-positioned replaced elements with auto width/height, both offsets specified, and no intrinsic size take their size from the constraint equation.
No resolution yet on what happens to replaced elements that have an intrinsic size; behavior here is more consistent, so need to check with other implementors (e.g. Mozilla).