Oh! Thank you so much for playing! Ah, we have actually removed the fullscreen button for now because the game would lag a lot in fullscreen for some reason!
Also, there is one ending that normally plays a cutscene in Unity's video player, but we recently found out that the video player is incompatible with WebGL, so the cutscene is replaced with just a black screen! If you'd like to see that ending properly, we highly recommend downloading the game!
Best of luck getting all of the endings!