Comprehensive instructions for how to run and edit the website are in the Ops Manual - https://uxbri.org/ops.
Once you've installed all the necessary Ruby & Jekyll global dependencies, you can run the site locally as follows…
# Install all Node dev dependencies
npm install
# Kick off initial local build
npm start
# Spin up a local server
npm run dev
# Need to spin up the Netlify CMS GUI?
npm run cms-local
# Build ALL files & assets to the `_site` directory
npm run build
# Output an unminified / uncompressed version of the stylesheet
npm run build:styles-dev
# Output a minified / compressed version of the stylesheet (for production)
npm run build:styles-prod