Sass is a very mature, stable, and powerful professional grade CSS extension language. It provides a superset of CSS with features like nesting, variables, imports and mixins.
Use TypeScript as your preprocessor. Write type‑safe, locally scoped classes, variables and themes, then generate static CSS files at build time.
Next Generation Frontend Tooling
Storybook is a development environment for UI components. It allows you to browse a component library, view the different states of each component, and interactively develop and test components.