Wondering if it’s possible to have these types of popups be effected by themes, and if so, how to do it? Is it possible using Firefox Colour?
The shape of the widgets (buttons, checkbox etc.) gets inspired by your OS theme. Unfortunately, as far as I know, Windows and macOS don’t allow adjusting this theme, beyond the color. On Linux and BSD, this is affected by the GTK theme.
Aside from that, yeah, I’d assume you can tweak it via the userChrome.css file.
You can have custom themes in Windows. The OS has full-fledged support for themes. Microsoft just doesn’t want you to know about it for some reason, but with a couple of web searches, it isn’t difficult to get it working and install custom themes.
Ah, I figured, they had that, because they change it themselves between OS versions, and programs’ widgets will automatically look different when you install them on different Windows versions, but didn’t know, you could change it yourself…
