MediaWiki non-theme-dependent CSS

Question

I use MediaWiki and I want to add some non-theme-dependent or "global" CSS; basically some display:nones,

It's a quick way to customize CSS without creating sub-themes (what I'd like to avoid due to a minimalist approach; it's also practically redundant for me in everything else beside CSS).

How can this be done without installing any extensions?

Answer 1

One can add global CSS without installing any extensions by navigating to Common.css:

https://example.com/MediaWiki:Common.css

Funny that I didn't find the file in the file tree of the MediaWiki directory.