Layout is really hard. Just tables by themselves are hard, even without any css around them. CSS makes layout impossibly difficult. I challenge anyone to keep the whole CSS spec and its associated behaviors in their head.
At this point css + html + javascript have become a dynamic PDL, and probably is one of the most complex pieces of software today.
As an aside, video decoding is offloaded onto hardware, so it's not as battery intensive as it used to be.
But implementing a layout engine is doable. CSS is not magic; there's a spec that can be (meticulously) transformed into code. I've occasionally showed code like this to people frustrated that CSS seems arbitrary, just to show them that there is a logic to the execution environment. Granted, you're not going to regularly click into it the way you'd click into the implementation of a library, but it's no different from something like React in that regard. I think it helps!
1. The most "core" parts of layout, like CSS 2 stuff, is pretty poorly considered with a bunch of weird features that interact in strange ways. (Floats and clearance? Margin collapsing?) Some parts of this "core" were intended to be universal even though they're a bad fit for other layout modes. (Margin and padding, for example, don't have a clear purpose for say grid elements.)
2. It's not well-modularized the way JS APIs are. A JS API can often be implemented fairly stand-alone, but each layout module interacts with every other layout module since they can be nested in various ways. I think newer specs like grid are trying to be stricter with this but there are fundamental challenges: the actual 2D screen is a shared resource that different layout modes must split up.
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?
Layout does not have to be so complex. There are dozens of GUI frameworks with simpler layout system. Those are enough for applications everyone uses.
This is technically but not usefully true with most videos on the web today.
The video decode itself is accelerated, but each frame passes through JavaScript to be composited.
The only time video is fully hardware decoded is when it's a simple video element to a static video file.
Lol, no way.
People are always "guess what JS does, wut."
Doesn't hold a candle to Cascading Stylesheets.