This addon isn't what it used to be. Now the only thing it does is not working! I installed 2 dark themes for Yandex and not only none of them appeared as "installed" in the addon (next to "library") but they also didn't have any effect on the yandex page.
Deleting from the browser, it's not worthy to waste my time with this crap.

Spyware; use Stylus instead.

Spyware

spyware people, spyware people!!!

Not only does this use an excessive amount of CPU (terrible battery drain on Android), it really should be removed from Firefox add-ons because it's spyware.

Made firefox 68 completely unuseable for me. If you still use it, back up your styles and try stylus instead, much faster.

Bad addon
Because of privacy

Very performance heavy, uninstalled because of it. Was taking like 60% of my CPU, and from what i've heard, is really invasive about privacy. So fuck it.

I mean, if you chose mozilla for privacy, don't choose this.

Using way too much CPU, disabling it dropped firefox idle CPU usage from 20-30% to 1-3%. (Tested on Ubuntu and Arch Linux, on an Intel i7 6th gen laptop CPU)

Can't download anything.

Our privacy is precious don't use Stylish, use Stylus (open source)

Doesn't need all this data access and thus, is getting deleted.

Fake

According to an explosion of articles on this extension: (one from robertheatonDOTcom) "since January 2017, Stylish has been augmented with bonus spyware that records every single website ... its 2 million other users visit"

Let that sink in... Every. Single. Website. Recorded and Saved.

My understanding was that they were removed from both Mozilla and Chrome stores. Shocked to see them back here after the base betrayal of their userbase. Shame on Mozilla for allowing this. This should be a lifetime ban!

Use STYLUS (github) instead. Use this extension at your own risk. (forewarned in forearmed)