lodisy Not something I actively do, but this would work
.TagTile-name {
background: #c5c5c5;
}
Obviously, change the background to suit.
Actually, just re-reading this, different backgrounds for different tag headers won't be simple, as there is no easy way of identifying the tag in question to make it unique. It would be possible to search for a specific string value using CSS, then change the background color accordingly, although this is horribly inefficient (although it would probably work)