How to create your own Firefox theme

Repack the file back into a zip file but change the extension to '.jar'. Install it like any other skin and you should see your modified toolbar. If you want to, you can now rework the other toolbar buttons. Colour changes are fast, simple and rewarding. Because button design is difficult if you're not artistic, another quick cheat is to download a selection of skins and assemble a custom collection of other people's button designs into a unique toolbar of your own. This is fine as long as you don't distribute the toolbar.

But what about the CSS? There's a lot of it, but a quick way to find the links between the various image files and the CSS placeholders that define where they appear in the browser frame is to do a global search. If you edit the 'browser.css' file, it's easy to see where the toolbar graphics fit in, and it's also easy to change the size and position.