Rave uses Bootstrap, a front-end framework. Bootstrap is assembled from its component files using LESS.
rave.less aggregates three files:
To keep customizations separate from the core, Rave integrators are encouraged to tweak rave-customizations.less, leaving the other files untouched.
When Rave compiles, LESS files are processed with wro4j to produce a single CSS file – rave.css.
The ability to perform client-side compilation (for quick troubleshooting on a development server) is upcoming. Once that's in place, rave.css can be minified during wro4j processing.