They're calling me the Ninja of On Your Feet 
(totally legit strat's used only, I promise)
Great game!

I noticed, at least in firefox, that the camera for the game seems to show some grey area outside the normal zone. I had the same problem with my game and was able to fix it by following this forum post https://forum.godotengine.org/t/exporting-to-itch-a-few-issues/100427/3 basically you just have to go into project settings > Display > Window and change the stretch mode from "disabled" to "viewport". Hope that helps!