Docker container for building static sites, using Jekyll and Gulp, including Bootstrap with SASS customisation. This gives you an environment in which to build Jekyll themes and sites without any reliance on CDNs.
Your Jekyll site should be available to the container under /app/site/
SASS customising bootstrap should be at /app/sass/style.scss
When the container starts, it will process the SASS customisations and emit CSS and font resoruces into /app/site/generated/
If you write your Jekyll theme to include the resources from that path, everything should just work.