To contribute to the website, you'll first need to install the extended version of Hugo.
The Hugo install page has instructions for different platforms and installers; make sure you end up with the extended version.
On Linux it may be easiest to pick up a tarball of the latest extended version from the release page and install it per https://gohugo.io/getting-started/installing/#install-hugo-from-tarball.
Next, clone this repository, and install the theme:
git submodule update --init
The development web server is started with:
hugo server
or
hugo server -D
to run the hugo server with draft enabled.
after which the site should be served at http://localhost:1313.
You'll see
error: failed to transform resource: TOCSS: failed to transform "style.sass"
if you don't have the Hugo extended version.
Submit pull requests first, those get run on Netlify and you can see a build preview by clicking on the details
link at the bottom.