Layout is so difficult that it made me quit using Common Lisp and ncurses to build my passion project and become the very thing I swore to destroy (a React developer).
I can't be the only one who wants a simpler layout language than CSS that's designed with two decades of hindsight to provide the maximum simplicity-expressiveness product. Are there any serious projects to engineer something like this, or has everyone given up and either embraced CSS3 (waiting for the LLVM backend) or gone back to plain text?
Author here, and I also teach web dev, including CSS, at the University of Utah (including this semester). Newer parts of CSS, like flex-box layout are both simple and powerful. Just use those! I think it's important to start thinking about learning all of the Web Platform like you'd think about learning all of the Windows APIs or all of the Linux system calls or all of your favorite programming language's features. People rarely do! (I have 15 years of Python experience, and I do not understand metaclasses or async.) There are lots of weird obscure corners, but you don't need to know those to build websites.
Check out laying out in Flutter: https://docs.flutter.dev/get-started/fundamentals/layout or Pax: https://docs.pax.dev/reference/layout/
Constraint-based layouts. The world's most sophisticated UI system uses that (Apple's UIKit).
I was playing with Solvespace a few weeks ago, and the thought occurred to me that the constraint-based modeling approach is exactly what I want in a layout system, and it extends to 3d even. We're stuck with CSS for now, but this must be the future.