In addition to changing themes, you can personalize Firefox even more by using your own toolbar background image. Add the following code to your userChrome.css file:
| QUOTE |
/* Use a background image for the toolbars:
(Substitute your image file for background.gif) */
menubar, toolbox, toolbar, .tabbrowser-tabs {
background-image: url("background.gif") !important;
background-color: none !important;
} |
It's easiest to place the image file in the same location as the userChrome.css file. The image can be of any image format supported by Firefox.
Found this
here.