Use this Add-On to replace Stylish! This is better!

I want you to be able to jump from about:addons to manage.html

Allows you to customize websites, and unlike 'Stylish', this extension does NOT have spyware. Very safe!

Easy to write your own styles, and easy to set where they apply. Easy to install styles, too.
Works exactly as I expect.
I like that you can set where a style applies at the bottom, in a list sort of thing.
It's very useful, I have a stylesheet for nearly every website I use frequently. I'm trying to get them all to match color palettes.
I will definitely continue using this add-on.

Great extension to fix site annoyances