Bulma - Bulma is an open source CSS framework based on Flexbox and built with Sass. It's 100% responsive, fully modular, and available for free.
MediaWiki - MediaWiki is a free software wiki package written in PHP, originally for use on Wikipedia.
Milligram - A minimalist CSS framework
TiddlyWiki - a non-linear personal web notebook
Material UI - A CSS Framework and a Set of React Components that Implement Google's Material Design
Confluence - Confluence is content collaboration software that changes how modern teams work