Apple's native SwiftUI framework and Google's Jetpack Compose framework stumbled upon basically the same layout system, "Constraints down, sizes up":

1. Proposal: The parent component proposes a size/constraints to the child

2. Measurement: The child component picks its own size based on those constraints

3. Placement: The parent component then positions the child in its coordinate space

It's all done in a single pass. It scales great. It fits great with React-like reactive UI frameworks. (SwiftUI and Jetpack Compose are based on React.)

This is what CSS needs.