The site is built by Github using Jekyll.
To preview locally, use the github-pages gem. Briefly:
# Ruby version must be >= 2.0.0.
ruby --version
# Install bundler for dependency management:
gem install bundler
# Fetch dependencies:
bundle install
# Start server:
bundle exec jekyll serve
# Get the most recent version of 'github-pages' gem:
bundle update
The only supported plugins are those that come with the github-pages gem.