But did you contact support so that they enable you to modify the CSS?
By default, it is locked.
That's the first thing the link I left you says. And I ask it again, because you do not clarify that you have requested and have been given access to modify the CSS.
The documentation says that your classes should start with "custom-"
I mention it because you say you used #custom, but the documentation says that the class must start with "custom-" and I don't see that in the code in the first link.
