Bulma

Bulma is a free and open-source CSS framework based on Flexbox, designed for rapid UI development. It provides a modern, responsive set of CSS classes to construct web interfaces without writing custom CSS from scratch. The project was created by Jeremy Thomas (GitHub user jgthms) and released in 2016; it is maintained by a community of contributors and distributed under the MIT license.

Bulma is written in Sass and emphasizes a modular approach. Its core is built around a responsive grid system called the columns and a range of UI components such as buttons, forms, cards, navigation bars, menus, tabs, and modals. Styles are applied through semantic classes with modifiers, for example is-primary for color and is-fullwidth for sizing. The framework is mobile-first and uses a flexbox-based layout so elements align and wrap predictably across screen sizes.

Because Bulma is CSS-only, it does not include JavaScript for interactive components; developers typically add their own JS or integrate Bulma with framework-specific components. Theming and customization are done primarily through Sass variables and maps, enabling broad visual changes with minimal code.

Usage involves including the bulma CSS file in a project, or installing via package managers such as npm or Yarn, then applying the relevant classes to HTML elements. Bulma's ecosystem includes official extensions and community plugins that extend components like tabs, modals, and carousels.

Bulma remains popular among developers seeking a lightweight, extensible styling solution that emphasizes readability and ease of use.