This framework uses Jekyll, Gulp, npm, less, and Bootstrap.
geosite-framework uses Jekyll to template out most of the user interface.
geosite-framework uses Gulp to compile its source less and javascript. Gulp concats and compiles less into css. Gulp concats and uglifies javascript.
geosite-framework uses npm to manage gulp dependencies.
less is a CSS pre-processor. It is also used by Bootstrap.
Bootstrap is a popular html/css framework.