Backport #25328 by @silverwind
EasyMDE in Firefox currently shows a ugly outline in the fake textarea
the CodeMirror uses. Hide it.
Before:
<img width="845" alt="Screenshot 2023-06-18 at 02 54 09"
src="dc406166-9ad5-4a9b-9581-002b5cdcc6df">
After:
<img width="870" alt="Screenshot 2023-06-18 at 02 54 24"
src="ddd78759-2cf2-4385-b863-7576fec25c34">
Co-authored-by: silverwind <me@silverwind.io>
Ran most of the Less files through the Less compiler and Prettier and
then followed up with a round of manual fixes.
The Less compiler had unfortunately stripped all `//` style comments
that I had to restore (It did preserve `/* */` comments). Other fixes
include duplicate selector removal which were revealed after the
transpilation and which weren't caught by stylelint before but now are.
Fixes: https://github.com/go-gitea/gitea/issues/15565
