82 -  CSS style guide

A proposed style guide to cover CSS code commits to the jQuery projects.  Open to suggestion for rules, this pass is based on the CSS in jQuery Mobile and jQuery UI.

Based off of Issue https://github.com/jquery/contribute.jquery.org/issues/82
> Okay, I was a little confused on this one, since I saw it done here:
> 
> https://github.com/jquery/jquery-ui/blob/master/themes/base/button.css#L109

I would say those are two separate comments. One that starts a section of workarounds and one that documents a specific workaround. I would have expected a blank line between the two comments there.

> Although on that note, do we want to go into proper commenting at the top of a css file?

I don't think so. If we do end up documenting the header comments, we'll want to do that in a shared style guide. The rules for comment headers are unrelated to the file syntax.