I spent a few minutes this weekend setting up some boilerplate and tools for the upcoming js13k contest.
I am planning to implement using atom and chrome with grunt for the heavy lifting. This repository https://github.com/ElementalSystems/js13kinit is a basic empty project set up for a mobile js13k entry.
The html is very minimal; striped down to the bare minimum that will play well with the mobile devices and won't throw any console warnings. I intend to work in scss and use sass to minify the CSS.