Build in Python on Django web framework with Twitter's Bootstrap, Modernizr & handlebars.
View source to see modernizr & yapnope.js at work and click about to see handlebars in action.
yepnope is an asynchronous conditional resource loader that's super-fast, and allows you to load only the scripts that your users need.
Handlebars provides the power necessary to let you build semantic templates effectively with no frustration.
Mustache templates are compatible with Handlebars, so you can take a Mustache template, import it into Handlebars, and start taking advantage of the extra Handlebars features.