Stephanie Eckles created a guide that covers new CSS pseudo-class selectors that currently have the best support, along with examples to demonstrate how you can start using them today.
Ethan Marcotte made a course that will help you learn how to use your development skills to build and support an effective and thriving design system.
Activate your free Stream Chat trial to start building today. Qualifying small teams and personal dev projects can also apply for the free-forever Stream Maker Account. 
Polypane is a standalone browser to guide your web development workflow every step of the way with built-in tools for responsive design, accessibility, meta information, and so much more.
Ricardo Oliva Alonso created a stunning, interactive 3d model of a kitchen using CSS.