Works great, but uses WAY too many resources. My laptop's battery drains very quickly and the CPU usage is always high whenever Firefox is open. The moment I uninstalled this extension, the CPU usage dropped back to normal. Will reinstall once something is done about this.
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)