You might think that just over a months worth of work went into this (it was, in theory), but it is a little more complex than that. We developed 2 frameworks, LeviRoutes and FormfactorJS and allowed us to push a lot of the common logic into a single controller. Using FormfactorJS it was possible to assign engineers to each distinct UI and have them work on it in isolation. FormfactorJS was used to specialize the base controller that was in every single page. If you look in our "scripts" directory, you can see how we structured the project - controller.js is common across all interfaces, desktop/controller.js is then dynamically injected at run-time and using prototypal inheritance we added custom formfactor specific features (such as swipe detection in the case of tablet and mobile)
In total we had 4 engineers working on the project, each working on their own UI. Each engineer spent roughly 20% of their time developing the parts of the UI that they were responsible for.
In all, it took just over a month of man effort to develop this application.