I often get questions about how can a particular web part be branded separately from all the rest or be branded by type. For example you want every Contacts list to have a green header bar instead of a tan header bar. Or perhaps you want a column of web parts on a page to look different than the main area that contains other web parts.
The latter I have always had a solution for, the former I figured out something today. As with everything that I focus on, these are "no custom development" / "no .NET code" solutions. You can usually build whatever customization you need with custom code. If you would like to just rely on CSS however, here you go....
Controlling Single Web Parts with CSS