I do this too, manually edit CSS on some sites to improve my reading experience. I do the same for removing fixed header menus that reduce the height of readabl

I do this too, manually edit CSS on some sites to improve my reading experience. I do the same for removing fixed header menus that reduce the height of readable content. And sometimes fonts. Today I found an extension (on Chrome) that lets me keep my CSS changes per site - probably there's something similar for Firefox.