Do you like skinning? Do you want to skin Gmail on your Firefox Browser?
HERE you can find all the instructions to do this... it's really a simple task:
- Install the URLid Mozilla/Firefox extension.
- Download this CSS file.
- Locate your profile folder and the
chrome folder within that. - Copy the downloaded CSS file to the
chrome folder and rename it to userContent.css (if you already have such a file, you will have to merge the two). - Restart Firefox.
- Visit Gmail.
The result? This: 
