Customized github minimal theme. Built using Docker to avoid the annoyance of maintaining a local ruby development environment (with apologies to lovers of Ruby).
To update jekyll package versions (Gemfile.lock):
docker run --rm --label=jekyll --volume=$(pwd):/srv/jekyll -it jekyll/jekyll:pages bundle update
Then rebuild the custom container (relies on existing/accurate Gemfile.lock):
docker-compose build
docker-compose up