Batter is a starting point for creating front-end themes for Pancake App. It is essentially the default front-end Pancake theme with most of the superfluous HTML/CSS stripped out. Batter is setup so Gulp does all the heavy lifting to compile Stylus and JS.
Make sure you have Gulp set up correctly, there some instructions here. After everything is set up run
npm install
gulp
The rest should take care of itself.
Since Gulp is taking care of minification automatically, the css and js folders in the root directory can be ignored for the most part as Stylus and JS from src will be minified there directly. All CSS and JS changes can be made in src/stylus and src/js.