Changes to [[MediaWiki:Common.csss]]

I've had to revert your changes to MediaWiki:Common.css as I could not understand what the purpose of them was and they appeared to remove other styling.

It is okay to make changes to these pages, but please do them in steps if you are changing large amounts, ensure that existing style that you do not intend to change remains in place, and write a detailed summary describing what changes you have made. Please don't just replace the entire page as there are many custom changes in it. Thanks!