I'm sorry if I implied that you are back in the stone age because you use IE, you're not. If IE does everything you want it to, then that's fine. But there's no harm in removing the straitjacket to try on another type of jacket, you might find a better fit. : )
Personally, I like Chrome. Sometimes it's a pain in the ass, maybe all browsers are at times, but for what I do, especially messing about with HTML etc. the developer tools are great. (I think all browsers have developer tools).
The Stylish extension is not responsible for my profile page background, anyone who has a little HMTL & CSS knowledge can do it without the need for any extension. Installing Stylish and using it to change how things look on a webpage only changes it for you, no one else sees what you see, unless they have the same extension and the same styles installed.
Thank you. : )