MediaWiki wikis lack full functionality without templates, styling, etc. Users have to export templates and linked templates from Wikipedia (or elsewhere) and import into their own installation. The users break Creative Commons licensing when the imports are too large and then omit the history for a successful import. This also make an ugly mess with multiple incomplete bits of Wikipedia all over the destination wiki. The worst example being after importing MediaWiki:Common.css when viewing the wiki with WebKit it displays Wikipedia's logo instead of its own.
The worst example being after importing MediaWiki:Common.css when viewing the wiki with WebKit it displays Wikipedia's logo instead of its own.
If you import a random page into your wiki which does XYZ, why are you surprised when it does XYZ? :P The first question is "Which underlying problem do you try to solve by importing MediaWiki:Common.css from some other website into your wiki site?"
Anyway, what you seem to be after sounds like T165195 to me, hence I am going to close this task as a duplicate.