3686 Extra padding on fandom tags in work blurbs when in a listbox

http://code.google.com/p/otwarchive/issues/detail?id=3686

We were trying to put padding around the listbox heading (that is, where it says "Recent works") but didn't get specific enough in the CSS, so it was affecting all things with that class.

With bonus removal of `margin-top: 0`, since `margin: 0` includes the top margin.
I'd be inclined to keep it as-is (darker grey), since #222222 against #FFFFFF has more contrast and is more accessible than #666666 against white. (The dark grey meets AAA standards, while the lighter only meets AA.)