Hey, this works!
I made a couple of Chinese language games in Squiffy. Each time, I foolishly uploaded the fonts I needed into the zip file along with font face instructions. Fool that I am!
I could have simply uploaded the fonts in my first game and then put this one tiny line at the top of all future CSS files:
So if you have a certain way you like your games to look, don't keep reuploading the same stylesheet. Just borrow from yourself!
Now that's a smart question! Weirdly, it's working for me on the http site but not on the https site. Maybe it needs a few days to update? I'll check up on it again tomorrow.
Edit: Oops. I should have used https in the actual @import line. Of course now I have to wait a long time for that to update.
Edit 2: Yay! It updated within a couple of hours and it works. So just be sure to use the https stylesheet.