As this site is hosted via a Github Pages sub-project you need to run it locally using the following command to ensure all links work as expected:

bundle exec jekyll serve --incremental --baseurl ''

Docker

To check website locally using Docker comment the following line out of _config.yml so the images load:

baseurl: /

NOTE: this change shouldn't be committed.

Then execute the following commands from the root of the project:

$ export JEKYLL_VERSION=3.8
$ docker run --rm --volume="$PWD:/srv/jekyll" -p 3000:4000 -it jekyll/jekyll:$JEKYLL_VERSION jekyll serve --watch

Website will be available at http://localhost:3000