This bug tracks the work necessary to support the draft CSS Scoping Module Level 2 specification: https://drafts.csswg.org/css-scoping-2/
<rdar://problem/82359096>
I believe this can be closed as all the work has been done in other bugs. Maybe this can be turned into an umbrella bug with all bugs matching this search: https://bugs.webkit.org/buglist.cgi?bug_status=__all__&content=%5Bcss-scoping%5D&list_id=10322921&order=Importance&query_format=specific
Yes -- we should have closed it previously. Thank you for catching this!