I'm a big fan of the open source (and free) Safari extension "Userscripts." I've had no issues using userscripts downloaded from nearly any website.

But how do we get remote CSS to work?

I can manually copy userstyles from userstyles.org for example and do some editing to the metadata to ensure the site-specific rules will function. But this means any updates/changes will have to be manually noticed and installed by me. Isn't there a better way? When I use Stylish (on Chrome), I can effortlessly add pre-made userstyles that stay auto-updated.

It seems like Cascadea on the App Store is what I'm looking for, but I like the inclusion of userscripts (and the free pricetag) so I'm wondering if I'm doing something wrong. Do any users have a more simple way than manually copying/pasting the raw CSS code from userstyles.org? I've tried "Install style as userscript" from there, but the site-specific compatibility rules never transfer over.