Nothing, because web applications are by definition html css js. Though canvas-based solutions can circumvent the layouting problem, but at the price of reinventing everything in a non-standard way.

The layout problem isn’t css... it’s the user platform is anything from a tiny vertical screen to a giant horizontal one.

Swing, Qt, et al do not have great answers to this problem, and definitely not superior ones than css.

qml is quite awesome. hands down! its a joy to work with.

but I agree in general with your statement.