Via Common.css the following css is included:
@import "//bits.wikimedia.org/static-current/skins/common/shared.css";
After advice on irc, tried to pull a copy to use locally from:
https://github.com/wikimedia/mediawiki-core/blob/master/resources/src/mediawiki.legacy/shared.css
But that still gives wrong layout, so probably not the correct version. Will need more searching to find the right one again.
Version: unspecified
Severity: normal
Loading raw css files hasn't been the standard practice since 2010.
Instead of requesting the raw file directly - which is unsupported (MediaWiki can change this at any time with no announcement, this is not a documented interface) - Use ResourceLoader instead, for example:
This avoids requesting raw files and forces you to make the same decisions the wiki software does (pick a specific wiki, language and module name).
Advantages:
Regardless of whether the wiki upgrades to a newer version and whether the files are moved around internally (or split up into several files), it will continue to work as expected.