I guess I would disagree right back.
All you can do in CSS is make things invisible and change size/positions and so on. My point would be, I suppose, if you take a webpage which is perhaps 350k of content and use CSS alone to jam it all in an iwatch, you are still left with having to hide large chunks of data, and still require 350k of space right?
I can’t see how you can take optimized content for a large screen, and just CSSifiy it to a 1.5" circle screen. There is a point at which your entire design philosophy has to change for the medium I would think. Especially if your content is heavily based on a multi-column layout which is hard to merge into single column no matter how you slice it.