Escapes don't work. Adding even a single escaped forward slash in a class basically just crashes the whole thing.

[blueshack112]

This example above works perfectly.

Adding a class name like this in the css that is loaded by inlinecss causes an error. I don't have the time to look into code but I'm guessing it is either replaced by a '\\' (lol I first used double backslashes and even GitHub's editor escaped those into a single blackslash. Edited it to four backslashes.) by python (autoescape of python string) or python string reads as just '/', essentially fulfilling the purpose of the escape at an earlier stage then where it was supposed to be used.

This is the error I get