I added the tampermonkey I think the next day after working out in JS how to change the images to the better quality ones. Stylish only allows custom CSS and what I needed was something that was able to handle JS so I went with making a User Script and using TamperMonkey.
I also have a list of how to install it. It now resizes the avatars to 120x120, but if you want the original 75x75 ones, just use this: https://pastebin.com/iqwa8pwL
Let me know if you have any issues. 