I recommended this CSS course last year, and now it's 50% off! https://css-for-js.dev/
There's so much content that after a year of starting it I'm still not done :O (I dedicate 1 hour/week). And I still enjoy it like the first day.
If you're curious, you can read about my experience thus far: https://noeldemartin.com/tasks/learning-css
This is an instance-of-one managed by Noel De Martin.