Emotion CSS Library

Emotion is a performant and flexible CSS-in-JS library for React and other JavaScript frameworks, created by Kye Hohenberger in 2017, providing CSS authoring through template literals, object syntax, and styled components, with features including automatic vendor prefixing, server-side rendering, critical path CSS extraction, nested selectors, media queries, keyframes, theming through context, component composition, and source maps, designed as a high-performance alternative to styled-components with smaller bundle size and faster runtime, adopted by companies including System, Glossier, and Storybook for their styling needs. The CSS authoring supports two primary syntaxes including the css template literal function for creating class names from CSS strings, and the styled component factory for creating styled React components with co-located styles, with both syntaxes supporting JavaScript interpolation for dynamic values, nested selectors through standard CSS nesting syntax, media queries, pseudo-selectors, and the automatic handling of vendor prefixes through the stylis CSS preprocessor. The theming system provides a ThemeProvider component that makes theme values available through React context, with the useTheme hook for accessing theme values in any component, and the css function automatically resolving theme references in interpolated values, enabling consistent theming across the application. The performance optimizations include the babel plugin for converting runtime styles to static styles at build time, the swc plugin for Rust-based compilation, and the zero-runtime approach through label and source maps for production builds. The server-side rendering with critical CSS extraction. The component composition through the as prop. The global styles through the injectGlobal function. The keyframe animations. Designed by Kye Hohenberger. Designed for React developers.