I recently implemented a similar concept to this for HTML emails at shortwave.com, it only works for the subset of non table emails (which we assume are marketing emails and you want to see the full HTML). It allows us to render stuff wayyy faster (especially on mobile where webviews are not cheap). We don't go all the way to pixel layout because we want to have some responsiveness, but it allows for heavily normalized emails (no more neon yellow on a green background with comic-sans font) and some other neat optimizations.

Didn't use yoga but a from scratch implementation. A good starting point is let's build a browser engine [1]. I hope to blog about it at somepoint.

[1]: https://limpet.net/mbrubeck/2014/08/08/toy-layout-engine-1.h...