The project contains a Vagrantfile which you can use to setup a Vagrant environment with a preconfigured Wordpress.
More on Vagrant; https://github.com/brthrs/brthrs-vagrant-box.
We use Sass as a CSS preprocessor. A Compass config can be found in the root of the project.
More on Sass; http://sass-lang.com, and Compass; http://compass-style.org.
The theme is build upon Bootstrap. The Sass flavoured Bootstrap that is.
More on Bootstrap; http://getbootstrap.com.