PeekCSS от Leon Grass

PeekCSS is a Firefox-native CSS inspector — hover any element to read its
computed styles instantly, no DevTools required.

Free, no account needed: hover + click inspection, grouped CSS with
copy, contrast ratio badges (AA/AAA), and basic color/font info.

Free account unlocks: full page color palette, complete fonts panel,
and accessibility scoring.

Pro adds palette export (CSS/SCSS/JSON/Tailwind), font pairing
suggestions, asset downloads with "download all" ZIP, and inspection
history.

Privacy-first: nothing about the pages you inspect ever leaves your
device. The only network call is an optional license check if you've
purchased Pro.