Bulma

Bulma is a CSS framework that provides a set of CSS classes in order to rapidly build styled websites. Bulma's use of pre-made classes means that you don't need any CSS-knowledge before diving into the framework, though it is still possible to costumize and extend it to one's liking.

A big benefit of Bulma is that it is only CSS-based, making it easy to use with any JavaScript framework such as React og Vue.js, although there also exist community-made libraries made specifically for those frameworks.