Igalia's Brian Kardell and Eric Meyer discuss what's caught their eye in CSS of late...
Mentioned Links
Hairline proposal
Eric's blog post
Item Flow, Part 1: A new unified concept for layout
CSS Custom Functions
CSS fragment references in HTML proposal
CSS @sheet proposal
CSS Pseudo Elements IDL Design
CSS Anchored Fallback Container Queries Explainer
Using container scroll-state queries
Disallow mix/random/tree-counting functions in some contexts #10982
Impact of masks on hit-testing needs to be specified #11339