@import really messes stuff up
So there was an issue with a style that uses an @import that was no longer available. Apparently, you can’t save a style when an @import doesn’t work, and if you get it while it’s working then lately the site goes down, your Firefox will hang at startup (!).
Because of this issue, I’m going to disallow styles on userstyles from using @import statements. With the update system that will be available in Stylish 0.4, it really shouldn’t be necessary to use @imports anyway.