pseudo-classes

Why is this an issue? Please provide more information.
This module does not validate css. That is the user's responsibility.

Sorry, my English is not good

Please see a picture:

The syntax highlighting is provided by the Ace editor. I would encourage you to review their issue logs for such a bug or submit one. https://ace.c9.io/

Marking this as closed since it appears to work as expected.

For anyone interested, there's a related issue in the Ace editor queue. It refers to complex selector support for :not(), but I assume this will be extended to :is(), :where() and :has(), etc.