u/Lncr1259in r/Frontend • Recommends
On “How to become a CSS positioning master???”
For flexbox I spent a good amount of time on Flexbox zombies. I don't think it's as well know as something like flexbox froggy or grid garden, but it's very helpful. It's a long game/tutorial, but it covers everything you'll want/need to know about flexbox.
For grid I'd recommend any YouTube videos by Jen Simmons. They are long and not in a typical tutorial format but very insightful. I would start with the "Basiscs of CSS Grid" video. If that's not you style, Kevin Powell also has good content on grid.
For positioning I started with the tutorial on the Web Dev Simplified channel.