How can i hide my display/screen resolution from websites? I use Firefox in windowed mode not with my default screen size but websites know my default resolution. This can be used to identify my pc. I dont want that for privacy reasons like tracking and adverstising. How can i prevent this? I found many threads/posts about this in various forums/websites. They are talking about Tor Browser and that websites can identify you if using full-screen mode. But as i said, im using Firefox not Tor and while im using windowed-mode websites still know my default resoltion. I tested this on https://whoer.net/ Another question, how can i restore the default window size in Firefox?