Hi, the default is light blue, so I suspect you are using a theme, or it might be caused by an add-on. So see what it is like in Safe Mode, which temporarily turns off hardware acceleration, resets some settings, and disables add-ons (extensions and themes). '''If Firefox is open,''' you can restart in Firefox Safe Mode from the Help menu: * Click the menu button [[Image:New Fx Menu]], click Help [[Image:Help-29]] and select ''Restart with Add-ons Disabled''. '''If Firefox is not running,''' you can start Firefox in Safe Mode as follows: * On Windows: Hold the '''Shift''' key when you open the Firefox desktop or Start menu shortcut. * On Mac: Hold the '''option''' key while starting Firefox. * On Linux: Quit Firefox, go to your Terminal and run ''firefox -safe-mode'' <br>(you may need to specify the Firefox installation path e.g. /usr/lib/firefox) When the Firefox Safe Mode window appears, select "Start in Safe Mode". ;[[Image:SafeMode-Fx35]] '''''If the issue is not present in Firefox Safe Mode''''', your problem is probably caused by an extension, theme, or hardware acceleration. Please follow the steps in the [[Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems]] article to find the cause. ''To exit Firefox Safe Mode, just close Firefox and wait a few seconds before opening Firefox for normal use again.'' xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx If that doesn't help, in order to better assist you with your issue please provide us with a screenshot. If you need help to create a screenshot, please see [[How do I create a screenshot of my problem?]] Once you've done this, attach the saved screenshot file to your forum post by clicking the '''Browse...''' button below the ''Post your reply'' box. This will help us to visualize the problem. If your question is resolved by this or another answer, please take a minute to let us know. Thank you.