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.
If it doesn't make sense, or if it seems an odd choice, chances are it wasn't intentional. I would go for consistency, whatever it means in this context. (Something that targets only direct descendants, in this case.) But I defer to you, so if you think it's fine, I'll merge it.