hey! great art and cool cozy game! If you want some good tutorials for gamemaker, here is the fullscreen for browser (It is cool to have it for game jams cause people have different screen sizes)
and here is how to do a good pause for your game (though you will have to think a bit because the draw_gui we have to use for the pause menu won't scale according to the full screen in html, so you have to scale it with some formula)
I make all my games with gamemaker so if you want some advices (though I'm not an expert) you can ask me if you want!