Update sucks! All custome styles are gone and no hint or help how to get them back working.
stylish once was a great tool for having a quick overview on different servers containing the same web-app.
Now this is gone. Thanks to fu***** Mozilla updates and constantly "improving" of the Firefox.
So now it's time to say ggodby and switch to chrome and using hopefully better addons there.

Seriously the worst update ever, I wish i could go back to the previous version, this is aboslute trash. You removed the ability to edit the actual browsers CSS, but guess what, the one I had got completely fucked up, and i cant go and remove it or edit it. so now im stuck with huge ass tabs and it looks ugly as hell. with no way to fix it, Also i had old styles just sitting there, THE UPDATE ENABLED THEM ALL so i have to go and figure out which one I was currently using as they are all applied fucking up all the sites, seriously WHY FIX SOMETHING IF IT WORKED FINE TO BEGIN WITH you ruined something great good job shit for brains

I couldn't install new themes. I tried multiples, but it didn't work at all.
Also I prefer the previous version of Stylish because it was easier to use and make a new theme.
Now Stylish isn't as good as before.

Tried multiple styles. None of them would install at all. Looks like the extension itself is broken and not the styles.

Well I can no longer edit the about:newtab page, presumably because the WebExtensions API doesn't allow one to modify said page. This is a major flaw as the default newtab page is hideous and retina-burning bright.

Doesn´t work with Firefox ESR 52.4.0. :(

I do NOT like the new version. It will NOT install themes nor customize. I had to go back to the previous version.
After going back the previous version. When I start my computer it updates and it doesn't work. Everytime I start my computer it updates.

Last update broke it badly. Worthless now.

Still broken with ESR 52.4.1 (64 bit).
Blank menu and only Chrome offered if you follow the link that appears when the Stylish icon is clicked.

The change to version 3 of this great extension is horrible. I — like many power-users — have a lot of custom themes, including a theme for the Firefox chrome (rather than a standard Firefox theme) and all of that simply broke.

Sure, I might be able to manually do the work to get things back to how I like it, but that is a ton of work just to get things back to normal again. NOT WORTH IT.

I plan on sticking with Stylish 2 and Firefox 52.4.0 ESR for the foreseeable future. I am really not a fan of this WebExtensions API change. We use Firefox because it does exactly what we want and gives us a lot of power and control over our web browsing experience. Please don't make more work for us by breaking custom-built themes.

Sadly can no longer use. I'm no longer allowing any extensions to access all data for all my websites. I understand needing access to the code to display the page, but I don't understand you needing my passwords and login names. Is there anything you can do to close that security gap? Thank you very much...D

WTF with this shit, I upgrade and all my styles are gone ..
Then, when I copy the saved styles and then edit them, they are no longer compatible, yellow warning symbols appear, what fuck you did ???? OMG ...
In the HP you only have a styles for Chrome, I don't need styles for it, just for FF OKAy !!! I had to go back to the previous version ...

P.S. Don't install the update

cool

After installing 3.0.1, all previous styles disappeared. Re-installed 2.1.1 and hey presto everything was working again.

After the re-release of the overhauled version, I cannot get this extension to work. It breaks core Firefox functionality (trying to customize icon positions, etc. does not work--Firefox goes into an unusable state if I try). It also will not save my styles when I try to manually import them--the save button does nothing at all. I can't even install new styles from userstyles.org--it just takes me to the addon installation page here on AMO.

New UI is a major step back from the simplicity and functionality of v2. The beautified dual panes make it hard to find a style quickly because of the large thumbnails forcing you to scroll through a limited sized area, the Library pane is quite useless. The sectioned code editor creates more work for you.

I was shocked, after the update all gone. Share to find ways:
The key is the stylish.sqlite file. Use tools to manually import according to the situation after opening

Updated itself to a version incompatible with previous storage method.
The only way to restore all my styles was to re-create each one and copy it by hand. Ridiculous.
Luckily I've found an export script (ExE-Boss/export-from-stylish.py) that allowed me to import everything to another user-style manager.