Read all about this on this blog post.
Clone the repository , open the terminal and type:
npm install and then
npm install grunt-postcss autoprefixer cssnano
this will take care of all the dependencies.
The gems used in this project are Sass, Compass, Jekyll and Wdm. If you don't have already installed them, type each of these commands in the terminal (anywhere):
gem install sass
gem install compass
gem install wdm
gem install jekyll
gem install jekyll-paginate
When you're done, open two terminals in the root of this project's folder and type
jekyll serve on one and on the other type