Ask HN: Strategies for single source HTML5 mobile apps?

Is it even possible? Most of the js toolkits like Jquery Mobile say they are cross platform and cross device ready, but none of them actually look and feel like a WEB app (They look awesome on desktop browsers but you probably need a little more on a desktop web app). The widgets and buttons look nice on mobile devices but I was wondering have people actually built applications with single source and if so how and what were some UI design strategies and methods you employed.