PT - clean css

What does this MR do?

As a preparation to issues0#355

This MR is cleaning up our self written CSS files.

How confident are you it won't break things if deployed?

hmmmm, lots of auto fixings. Looks good in localhost so far. I have resolved several errors in writing of CSS properties. This could of course result in single occurrences of wrong font size for example. Nothing I would worry about and what cannot be fixed easily if found.

Checklist

• added a test, or explain why one is not needed/possible... (test only visibly possible)
• no unrelated changes (just very few browns changed and mixed into it by accident)
• asked someone for a code review
• joined #foodsharing-beta channel at https://slackin.yunity.org
• added an entry to CHANGELOG.md (description, merge request link, username(s))