Need ability to ban one or more users from a category

[meriksson (Martin Eriksson)]

@pfaffman

If you really can’t just kick them off, maybe create a not-allowed-in-xxx group and then use CSS to hide their posts in that category?

Thanks for this suggestion!

Can you give some hint on how to implement it?

As far as I know group memberships are not indicated with HTML attributes. Is there some other way for CSS to detect whether or not someone is a member of a particular group?