CSS / Sass

CSS (Cascading Style Sheets) is the standard language for styling web content, maintained by the W3C. Together with HTML and JavaScript, CSS forms one of the three core technologies of the web platform. Modern CSS (2024–2025) has evolved significantly with features like container queries, cascade layers, the :has() selector, native CSS nesting, subgrid, color-mix(), individual transform properties, and view transitions — reducing the gap between CSS and preprocessors.

Sass (Syntactically Awesome Style Sheets) is the most widely adopted CSS preprocessor. Its SCSS syntax uses familiar curly braces and semicolons, making it fully compatible with standard CSS, while the indented .sass syntax uses whitespace instead. Although native CSS now supports variables and nesting, Sass still provides powerful features like mixins, custom functions, and a module system that go beyond what the browser offers. PostCSS takes a different approach as a plugin-based CSS transformer, powering tools like Autoprefixer and CSS Modules — and serving as the foundation for Tailwind CSS.

The MDN Web Docs provide the definitive CSS reference with browser compatibility tables, tutorials, and interactive examples. For Sass, the official Sass documentation covers the language, built-in modules, and migration guides. The PostCSS repository maintains a plugin directory and usage guides for integrating CSS transformations into any build pipeline.