Bulma

Bulma is a free, open source CSS framework built on Flexbox and Sass. It gives you ready-to-use layout and component styles without requiring any JavaScript.

Bulma provides classes for columns, buttons, forms, navigation and other interface pieces. The layout is responsive and designed mobile-first, so pages adapt to smaller screens without extra work. Themes and values can be changed through Sass variables or CSS variables. The project is maintained on GitHub, and the docs include examples you can copy into a page. Because it is only CSS, interactive parts such as menus need your own scripts, which keeps the framework light.

• Flexbox and grid based layout classes
• Responsive, mobile-first design
• Built with Sass and CSS variables
• Dark mode support
• Loading skeleton styles

Developers who want a simple CSS framework without a JavaScript layer. Teams building a quick responsive website with little custom CSS, and beginners who want a clear set of classes to start with, will find it approachable.

Bulma is open source under the MIT license, so it is free to use. Because it is CSS only, interactive behavior such as dropdowns needs your own JavaScript. The site describes Bulma as a modern framework that does not impose a particular script library, so you can add the behavior you prefer.