I've been using this style - with some tweaks - for web apps too. I don't think I have it completely figured out yet, but it's promising so far. You can view the source of http://lofi.limo/ to see how it's working out.
This is the output of an app/templating system, i.e. not a single HTML page. Have you ever read the HTML of any dynamically generated page? It's unreadable.
All the HTML code in the app I maintain is pretty readable. At some point of complexity any HTML is difficult to parse, but if I hand-wrote a page in my app I think the HTML would be largely the same.