Like Windows 8? The theme Pseutro Light is meant to be a compliment to the entire Windows 8 experience.
The simplicity and subtlety of Windows 8 styling with a dash of Microsoft Design Language to give you the best of both worlds; a powerful desktop experience and an interface that blends in alongside native Windows 8 apps. Want to give it a shot? You can download Pseutro Light from the Firefox Add-ons website.