Bulma is a mature, well-established CSS framework (v1.0.4) built with Sass and based on Flexbox. It provides a comprehensive set of reusable UI components, layout utilities, and responsive design tools. The codebase is organized into a modular Sass architecture with clear separation of concerns: utilities (variables, mixins, functions), base styles, elements, form controls, components, grid system, layout, and helpers. The repository includes both the core CSS framework and a Jekyll-based documentation site with Cypress end-to-end tests. A notable feature is the Bulma Customizer, a React-based application that allows real-time customization of CSS variables through an intuitive interface. The framework emphasizes zero JavaScript dependency, making it framework-agnostic and easily integrable into any project.