Works really well for most sites, but I'd love to be able to tweak specific websites in finer detail than picking which dark mode style and color choices. Namely, making Google Docs/Sheets/etc UI grey and black but keeping the document content itself intact. It's annoying having to overwrite code in the dev tools every time I want to use Docs and preserve colors when formatting is very important (since those changes are wiped out once you close Firefox).

Dark theme detection also usually works but can be spotty.