I'm not so sure, I'm running Win10 and I've tried the forum on Edge, Chrome, and Firefox, all of which display the forum just fine. It looks fine on my cell phone as well which is an android. While I'm not in disagreement with you, it certainly could be the forum, but, it may also be some kind of setting on a users computer.
I dislike trying to troubleshoot stuff like this because it isn't consistent, kinda like you hear this noise in your car and when you take it to the mechanic, it stops, and the mechanic is left scratching his head as to what might be causing it.