Full screen video background no longer black

[itsbrokenffs]

When setting video to fullscreen, the background color is grey not black. So for any video that doesn't have the same aspect ratio, it will be grey bars around the video instead of black. Super annoying and I couldn't find the right line to fix - wasted an hour editing CSS files with no success. Uninstalling Shadoxfox was the only way to get full screen videos to display with proper black bars.

[overdodactyl]

I'm not seeing this on sites like youtube or streamable, do you have a sample link I could look at?