From what I understand, Stylish and Chrome still don't always like to play nice with each other. I don't believe you need to be using TamperMonkey to use the FF extension since there is a Stylish FOR Chrome as a stand-alone.
I do understand how you feel. I too am a very visual person and I HAVE to have my scripts to make IJ clean enough that I don't want to gag when I open any of my journals.