Thanks a lot for your reply, I'll try changing the image format as you suggested. If that doesn't work the only thing I've got left is trying to rescale the PNGs using photoshop. I don't know why but when rescaling them with an online app I always got fuzzy images.
I was intending to do an article on classical mechanics, mainly Noether's theorem and it's use to derive Newton's third law and conservation of energy, but since we can't use MathJax and this doesn't work I think I'm going to give up.