There's no reason for this to be inside MediaWiki:Mobile.css and MediaWiki:Common.css
I would suggest moving the margin and padding rules to the template module itself - https://en.m.wikipedia.org/wiki/Special:MobileDiff/711777560
Top loading the styles in Mobile.CSS will introduce another HTTP request and lead to a hit on first paint and overall page view performance so we should explore this carefully.
In the current implementation, as used by Vector, the CSS is broken out into a separate HTTP request for caching reasons. We should re-evaluate this as Vector would also benefit from having these CSS shipped in a single request.
Looking through the existing rules in MediaWiki:Mobile.css none of them with the exception of the hatnote rule need to be top loaded.
Hopefully, we'll have some bandwidth soon to investigate this. The RFC will alleviate most of these problems.