Steps to reproduce:

utilize e.g. https://www.avdweb.nl/templates/yootheme/css/theme.9.css in simple html page(see attached).
in 'Dev tools' open Style Editor and 'theme.9.css' in it

Actual results:

the stylesheet is minified and there are no controls to enforce 'pretty print' on it
(there are 2 line feedsin the css file. wiping them out gives pretty-printed stylesheet in Style Editor)

Expected results:

there should be an UI control(button/menu entry) allowing to force formatting(pretty print) over (script/)stylesheet - for the case FF improperly detects 'minified' state.

The Bugbug bot thinks this bug should belong to the 'DevTools::Style Editor' component, and is moving the bug to that component. Please correct in case you think the bot is wrong.