css-modules

The CSS Modules skill provides a robust architectural approach to styling modern React and TypeScript applications. It focuses on achieving true component encapsulation by generating locally-scoped class names at build time, effectively eliminating global namespace collisions. This skill is particularly optimized for high-performance frontend environments that leverage Vite, providing deep configuration patterns for Lightning CSS—which is recommended for its superior transformation speed—and traditional PostCSS workflows. It is the ideal solution for developers managing complex animations, styling third-party UI libraries, or performing large-scale migrations from legacy global CSS architectures to a maintainable, modular system. By utilizing the composition pattern, developers can share styles across components without sacrificing isolation, ensuring that design systems remain predictable and modular. The skill also bridges the gap between style definitions and static typing, offering configurations for generating TypeScript definition files, which provides autocompletion for class names and prevents reference errors during development. It serves as a comprehensive reference for mapping file naming conventions like *.module.css, configuring build-time class name patterns, and implementing global escape hatches when specific styles must persist outside of a component boundary. Whether you are building highly interactive animations or structuring a large-scale design system, this skill provides the necessary operational patterns for efficient, collision-free, and type-safe styling.

• Automated local scoping of CSS classes with unique build-time hashing

• Advanced integration with Vite, Lightning CSS, and PostCSS loaders

• Type-safe style imports via generated TypeScript definition files

• Composition patterns for sharing style logic across component trees

• Support for complex selector strategies including :local and :global scopes

• Vendor prefixing and modern syntax transpilation for cross-browser compatibility

• Class name pattern customization for production vs development environments

• Best for: Complex component animations, third-party component styling, and legacy CSS migration

• Input: Component-specific CSS or SCSS files following the *.module.css pattern

• Output: Encapsulated CSS bundles and imported JS style objects for React components

• Constraint: Requires Vite or a module-compatible bundler to process class name transformations

• Optimization: Use Lightning CSS to replace Autoprefixer and increase build performance by up to 100x

• Pro-tip: Combine with Tailwind CSS in a hybrid approach to leverage utility classes for layout while using CSS Modules for component-specific logic