Comment by troupo

> But these days HTML and CSS are basically inseparable and go far beyond "text is primary".

That "inseparable" is building on top of a bunch of legacy cruft, hacks and workarounds for a system that is stilm barely suitable to layout some simple text.

Just because CSS is there it doesn't make the browser a UI framework.

> I don't see why a browser would need to re-layout for just a focus change.

Indeed. No one does. And yet you'd be surprised: https://gist.github.com/paulirish/5d52fb081b3570c81e3a (note: unfortunately there's no up-to-date list as some of these issues are fixed in all or some engines, and a bunch of other gotchas are introduced).

> There is fundamentally very few differences between HTML+CSS and other UI frameworks.

Lol. There's almost no other UI framework that struggles with as many trivial performance issues as HTML + CSS [1]. No other UI framework has so many gotchas and issues with even the simplest layouts and animations. No other UI framework has warnings of "you have 800 nodes, it's too big, and will cause issues". No other UI framework has so few ways of telling the framework "delay painting" or "I will take over painting" or "do these paints in batches" or...

Etc. etc.

[1] A good article that dives into just the animation side of things https://motion.dev/blog/web-animation-performance-tier-list