Overview
UnoCSS is an instant, on-demand atomic CSS engine designed for speed and flexibility. Unlike traditional CSS frameworks, it features no core utilities by default; instead, all functionalities are provided via customizable presets. This makes it highly extensible and lightweight. It boasts high performance by avoiding parsing, AST generation, or scanning, making it significantly faster than alternative JIT engines. UnoCSS integrates seamlessly with popular build tools like Vite, Webpack, and PostCSS, and offers features like Attributify mode, pure CSS icons, and variant groups.
Key features
- On-demand atomic CSS generation
- Fully customizable preset system
- Attributify mode
- Pure CSS icons support
- Variant groups shorthand
- Interactive inspector
- CDN runtime build
- Extremely fast compilation
- Zero dependencies
- Highly customizable with presets
- Lightweight bundle size
- Rich integrations with Vite, Webpack, and PostCSS
- Requires learning preset-based configuration
- No default core utilities without presets
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