If you mess up the CSS, you might be no longer be able to restore a working version, because the buttons are no longer visible.
Notes for security:
Open two browsers. Or at least two different browser windows.
In browser 1, open the CSS wiki page. Then press "edit". Ideally move this browser to a different desktop (or use a different device / computer).
In browser 2, open the CSS wiki as well. Make your edits in browser 2. See how they look like. And if something totally breaks, so you cannot fix it in browser 2 anymore, go back to browser 1 and just press "Save page".
- currently NOT in use:
- currently in use: https://www.whonix.org/wiki/MediaWiki:Foreground.css