Many main pages use inline styles and templates to style
Or they add classes to the MediaWiki:Common.css page specific just to the main page and loaded on just the main page.
Most main pages look terrible on mobile and are difficult to fix. e.g. https://www.wikidata.org/wiki/Wikidata:Main_Page
We have a bunch of code in MobileFrontend to workaround this but I'm keen to destroy the code.
We should thus introduce MediaWiki:Mainpage.css which is only loaded on the main page with the ResourceLoader other group set. This would allow us to use media queries on the main page and remove this code debt from MobileFrontend.
Any thoughts? Any problems with such an approach?