I'm going through CSS: The Definitive Guide by O'Reilly, published in 2017 and I got this along with other O'Reilly books from a humble bundle back in Nov 2017. I'm using an incremental reading method to go through this book. O'Reilly really live up to their reputation for being awesome compsci books - I finished first chapter and it covered even the most obscure ways of doing things, such as linking stylesheets from Apache .htaccess. O'Reilly is well worth the money especially if you see any special bundle sales.