Very good contrast, no stupid color choices, a little interesting without being distractingly busy, and it's easy to tell which tab is the active tab. This is a surprisingly rare combination of features in a Firefox theme, and this Blue Nebula Space theme is by far the best example I've found.

good

I love this theme! I have used it for over half a year now. Very cute and also great contrast as well so I can see the tabs and texts for each tab.

Beautiful!

amazing and updated

Hey, that's pretty good!