Liferay has its own "design language" called Lexicon, the concept is similar to Material Design by Google.
It is a kind of philosophy to create a consistent user experience using recommendations:
A design language usually includes categories as:
- Color
- Grid (based on Bootstrap CSS)
- Responsive Layout
- Typography
Clay is the implementation of Lexicon built on top of Bootstrap.
- Translates LESS to SASS
- Includes a component library