I use this to write CSS to fix broken sites and remove overintrusive ads that escape ad blocker. Actually works, unlike new Stylish. Interface a bit clunky, hence 4 stars.

does not work on loaded local pdf files. stylus says "Firefox forbids access to the site, In Firefox 60 and newer you need to remove this domain from extensions.webextensions.restrictedDomains in about:config."

however the local files are not in any domain

Love this addon. Only issue is the editor window does not remember which monitor to open on in a multi-monitor setup nor the last used window size; in my case, maximized on monitor #2.

Very cool. The editor has live preview, syntax autocomplete, colour pickers, and different colour themes to choose from.
Can even use it to customise it's own UI, nice!

Very few working themes, most of them are out of date and either doesnt work or brakes the websites.

I like this plugin, but I want it too in mobile version of Firefox because some websites aren't responsive. Can you create a version for mobiles?

Brilliant, allows me to customize my most visited sites exactly how I want. Most of all it lets me live in my world of Dracula.

Used Stylish for ages, don't know why I didn't switch sooner. Besides not having the shady past of it's older counterpart, the coding environment is so much nicer, live preview, syntax autocomplete, colour pickers, customisable UI/UX.