1. Simple and flexible HTML, CSS, and JS for popular UI components and interactions

  2. The most advanced responsive front-end framework in the world

  3. A UI Component library implemented using a set of specifications designed around natural language

  4. A set of small, responsive CSS modules that you can use in every web project.

  5. Bulma is an open source CSS framework based on Flexbox and built with Sass. It's 100% responsive, fully modular, and available for free.

  6. A modern responsive front-end framework based on Material Design

  7. A lightweight and modular front-end framework for developing fast and powerful web interfaces

  8. A Beautiful Boilerplate for Responsive, Mobile-Friendly Development

  9. Lightweight, responsive and modern CSS framework for faster and extensible development.

  10. A rock-solid default for HTML5 awesome.

  11. Responsive HTML5, CSS and JavaScript Framework

  12. A utility-first CSS framework for rapidly building custom user interfaces.