I had a tussle with my PC today which locked it up including my Firefox browser. After a hard reboot the theme looks different. Settings reveals it's "System theme 1.2". On another PC I use the theme is "default" 1.1. That looks like what I had and prefer but I can't find it anywhere. In particular the background of the tabs is now all white and too white with no division seen between them. My other installed theme options are light, dark, and alpenglow. Actually the light theme looks like the system theme which states "follow the operating system settings for buttons, menus, windows." I can make no sense of that looking a my display settings. Dark is much too dark, and alpenglow resembles an unappealing fruit salad. I have no time to be creative as another theme option that's offered. Any idea how I can revert to default 1.1? I am using Win10 if it matters which updates often.