I tried to use HTML5, but for some reason it was super zoomed in. My viewport size might have something to do with it? All my viewports are 1366 by 768 (the default) and with windows it works fine. Should I change that so it will work?
Do you have view ports enabled? I had a similar issue because I forgot to make viewport 0 visible. Room's size shouldn't be causing problems if the window is size is correct.
HTML 5 is buggy I've had issues in the past with post processing bugging out but building it as a gx.games target, outputting as a zip and uploading it set as a play in browser game works just fine