This video tutorial from Kevin Powell teaches you to build responsive websites from scratch.

The course starts with explaining the core concepts needed to start thinking responsively, and then it takes you through every single step in building a professional-level responsive website.

You will learn about these essentials of building a responsive website, all while building a real-world project:

  1. How to approach a layout
  2. CSS Units
  3. Flexbox basics
  4. Media query basics

You can watch the full video on the YouTube channel (4 hour watch).