Try to:
- Reset Firefox Settings:
- Open Firefox and type about:support in the address bar.
- Look for the "Refresh Firefox" button and click on it.
- This will reset Firefox to its default settings, including removing any installed themes or extensions.
- Check GTK Theme:
- Make sure that the GTK theme you are using is compatible with the version of Firefox you have.
- Try switching to a default GTK theme to see if the issue persists. You can do this through your system settings.
- Remove or Update User Styles:
- The 'usercss' mentioned might refer to user stylesheets that can be applied to Firefox for customizing its appearance.
- Check your Firefox profile folder for a folder named chrome. Inside, there might be a file called userChrome.css. If you find it, try removing or renaming it to see if the issue is resolved.
- If you want to keep your custom styles, you might need to update them to ensure compatibility with the latest Firefox version.
- Check Firefox Launch:
- The fact that Firefox looks normal when launched from Discord may indicate an issue with how Firefox is started.
- Try launching Firefox directly from its icon or menu to see if the issue persists. If it doesn't, there might be an issue with how Discord is launching Firefox.
- Update Graphics Drivers:
- Ensure that your graphics drivers are up-to-date. Outdated or incompatible drivers can sometimes cause graphical issues.
- Check your system's software update tool or visit the website of your graphics card manufacturer to get the latest drivers.