Fullscreen Firefox Mac

Hi, i just started using my mac a few days ago, and for the past hour I have been looking through the menu in firefox to get into fullscreen mode. How do I do it, F11 just shows the desktop, ctrl+f, command+F, and option+f do not go fullscreen, and I cannot figure it out at all.

Javascript fullscreen api for Firefox 52.3.0 in Mac 10.13 beta 5 does not make the window go fullscreen completely Summary: javascript fullscreen api for Firefox 52.3.0 in Mac 10.13 beta 5 does not make the window go fullscreen completely.
This isn't a Firefox solution, but Plainview is apparently the only full screen browser for OS X. It has lots of unique features that aren't in Firefox, such as a presentation mode, where preset websites can be switched between using the keyboard, and a kiosk mode. It can also be run as a chrome free HUD window.

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