One great thing about this book is the 'stuff I didn't do' part.
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.
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