Dunno if this exists. Maybe I should write one?
The CSS 2 spec was actually a good introduction to the fundamentals, but it is 20 years out of data now, and the new modular specs does not works well as a tutorial.
I like this page: https://www.taniarascia.com/overview-of-css-concepts/
Where can I read about this - has someone written "CSS: the good parts", for example?