The site was built with the framework Bootstrap 4 and the theme Leap and the deployed version is on the gh-pages branch.
To develop and build the site locally you need to use CodeKit application while using the .config.codekit3 configuration file from the root of this repository.
This static site is deployed to GitHub Pages from the gh-pages branch. In order to push the local commit to the remote repository you need to pause the CodeKit app before committing, otherwise the .config.codekit3 file will be re-compiled by the app after the commit which modifies the branch again so it can't be pushed to the remote. More info about using CodeKit and Git together here.