Gmail Redesigned is a free style that completely changes Gmail’s look by overhauling the color scheme and adding new graphics:
We’re going to detail three various methods to get Gmail Redesigned. All of these methods require Firefox.
Google Redesigned is a free addon from Globex Designs (the creators of Gmail Redesigned) which changes both Gmail and Google Calendar. It’s also the best bet for easy updates and getting the latest version. Install from their website here.
Better Gmail 2 is another addon from Lifehacker which adds new features to Gmail. While it does not guarantee having the latest version of Google Redesigned, it does provide several other features in one extension. Install it from Lifehacker’s website.
Activate Gmail Redesigned by opening up Tools → Addons…
And hit the Skins tab, and make sure that Gmail Redesigned is marked. Then click OK.