To use: when you have the dependancies as per
the docs you should run
bundle install.
HTML files are based on Minima - if you need to configure the post or page layouts, copy those files in as needed.
Bootstrap variables can be overriden in _sass/custom.scss - refer
to the full list of available values.
Note that GitHub Pages doesn't run gems that aren't on their predefined list, so I included the source files of Bootstrap.