There are more themes available via the buttons in the Customize palette.

See:

• https://developer.mozilla.org/Firefox/Developer_Edition/Reverting

Thanks for your answer. Maybe I wasn't clear in my original post. I'm talking about the default theme. It is messed up (differs from the one on my colleague's pc) and I can't seem to restore it.

Please provide a screenshot of what you are seeing.

https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem

It is best to use a compressed image type like PNG or JPG to save the screenshot and make sure that you do not exceed a maximum file size of 1 MB.

Then use the Browse .... button below the Post a Reply text box to upload the screenshot.

Firefox 35.0a2 allows the user to toggle between two Profiles - between the Developer Edition Profile and regular Aurora [at least on my installation] on yours' it my be your Release version Profile.

The control is in Options > General and labeled Allow Firefox Developer Edition and Firefox to run at the same time

See attachment.

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes