SCSS

CSS extension language that compiles to standard CSS, adding variables, nesting, mixins, and other features to keep stylesheets maintainable. The SCSS syntax uses curly braces and semicolons and is a superset of CSS, so any valid CSS is valid SCSS.

Actively supported since 2006 by a consortium of tech companies and hundreds of contributors. Widely adopted across the industry, with frameworks like Bootstrap, Bourbon, and Susy built on Sass. Stands out among CSS preprocessors for its mature feature set, full CSS compatibility, and support for modular architecture.

Key features:

• Variables, nesting, and mixins for reusable and organized styles
• Partials and the @use rule for splitting styles into modules
• @extend and placeholder classes for shared declarations
• Math operators and built-in functions for responsive layouts
• Integrates with build tools: webpack, Vite, Rollup, and npm scripts

SCSS suits teams building design systems, maintaining large stylebases, or sharing design tokens across components. Fits cleanly into modern front-end pipelines, where compilation runs at build time and outputs plain CSS for any browser.