Hello, I've updated my Nvidia graphics driver and encountered this issue. Basically I noticed it on twitch.tv mainly, bottom of my website is hidden behind taskbar, as if firefox thinks I have the automatically hiding taskbar setting enabled, which I never used. I've tried deleting some json file from %appdata% which has not helped, tried reinstalling firefox, running in troubleshoot mode,disabling hardware acceleration and nothing helped. Here are screenshots of how it looks fullscreen and how it should look, as you can see the bottom section is missing. Thanks in advance