If you are looking for the best dark theme to decorate your Firefox browser with, take a look at Bloomind FT DeepDark 2. While the name does not roll off the tongue, it is the most downloaded Firefox theme at the moment via the Firefox Add-ons website.
Bloomind FT DeepDark 2 really transforms the look of Firefox 4+ for Windows users. It has been tested to work though on both Windows and Linux with little to no issues. The entire theme is very sleek looking. I hope to see more Firefox themes like it in the future that pay attention to detail and get every inch of the browser themed over like Bloomind FT DeepDark 2 does.
When push comes to shove this is a clean theme with cool colors. You can pick Bloomind FT DeepDark 2 up from the Firefox Add-ons website. If you’d like to see it in a different color, you might also browse through some of the other variations that have been released.