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Probably my favorite now. Soothing colors with just the right amount of variation. And the tab titles show up well!

Perfect !

很美

Very simple theme that doesn't require a flashlight to read the bookmarks toolbar!!

This is fantastic. I woke up one day to find the most hideous colors in back of my tabs. Not in the tabs, but behind them. Don't know why that happened. After some googling, came across Clear Transparent Glass. Not only did it eliminate the colors, it has been impact-free on Firefox: no ripple effects, no distortions, nothing. As opposed to Simple White, which squared off my tabs and had other unwanted effects. Clear Transparent Glass is a wonderful theme if you are looking for a plain background or if you are not happy with the colors being foisted on you.

Perfect. Makes everything clear: Toolbar text, buttons etc. Liiiiike it! I use it!
Update (Aug 2013): Don't use it anymore. Don't remember why.

That's funny, but this one is my favourite theme for FF ever. I just can't work in FF without clear transparent glass theme. =D
Thanks for such a simple and pleasant theme!