# Lightning CSS — Blazing-Fast CSS Parser and Minifier in Rust

> An extremely fast CSS parser, transformer, bundler, and minifier written in Rust, designed to replace PostCSS and Autoprefixer with a single tool.

## Install

Save as a script file and run:

# Lightning CSS — Blazing-Fast CSS Parser and Minifier in Rust

## Quick Use
```bash
npm install lightningcss-cli
npx lightningcss --minify --bundle --targets '>= 0.25%' input.css -o output.css
```
```javascript
import { transform } from 'lightningcss';
const { code } = transform({
  filename: 'style.css',
  code: Buffer.from('.foo { color: oklch(0.7 0.15 180) }'),
  minify: true,
  targets: { chrome: 95 << 16 }
});
```

## Introduction
Lightning CSS is a CSS parser, transformer, bundler, and minifier written in Rust. It handles vendor prefixing, syntax lowering, CSS modules, and minification in a single pass, replacing the need for PostCSS, Autoprefixer, and cssnano while running orders of magnitude faster. It is used by Vite, Parcel, and other build tools.

## What Lightning CSS Does
- Parses CSS into a typed AST with full spec compliance and error recovery
- Automatically adds or removes vendor prefixes based on browser targets
- Lowers modern CSS syntax (nesting, color functions, cascade layers) for older browsers
- Bundles CSS @import rules into a single file with dependency resolution
- Minifies CSS with structural optimizations beyond simple whitespace removal

## Architecture Overview
Lightning CSS is implemented in Rust and compiled to native code and WebAssembly for Node.js and browser usage. The parser produces a typed AST where each CSS property is represented as a Rust enum variant, enabling type-safe transformations. A single pass over the AST handles prefixing, syntax lowering, and minification simultaneously, avoiding the multi-pass overhead of PostCSS plugin chains.

## Self-Hosting & Configuration
- Install the CLI with `npm install lightningcss-cli` or the library with `npm install lightningcss`
- Set browser targets using browserslist syntax or explicit version numbers
- Enable CSS modules with `cssModules: true` in the transform options
- Use the `bundle()` API to resolve @import dependencies into a single output
- Integrate with Vite via its built-in Lightning CSS support or with Parcel as the default

## Key Features
- Written in Rust for native performance: 100x faster than equivalent PostCSS setups
- Single-tool replacement for PostCSS, Autoprefixer, cssnano, and CSS modules plugin
- CSS nesting, custom media queries, and oklch color lowering for older browsers
- CSS modules support with scoped class names and composition
- Available as a CLI, Node.js API, Rust crate, and WASM module

## Comparison with Similar Tools
- **PostCSS + Autoprefixer** — plugin-based and slower; Lightning CSS handles all transforms in one native pass
- **cssnano** — minification only; Lightning CSS also prefixes, lowers syntax, and bundles
- **Sass/Less** — preprocessors with custom syntax; Lightning CSS works with standard CSS
- **Tailwind CSS** — utility-first framework; Lightning CSS is a low-level CSS processing tool
- **esbuild CSS** — fast but limited CSS handling; Lightning CSS has deeper spec compliance and more transforms

## FAQ
**Q: Can I use Lightning CSS with Vite?**
A: Yes. Vite has built-in support for Lightning CSS as its CSS processor via the `css.lightningcss` config option.

**Q: Does Lightning CSS replace PostCSS entirely?**
A: For most use cases (prefixing, nesting, minification, modules), yes. Custom PostCSS plugins may still require PostCSS.

**Q: What CSS features does it downlevel?**
A: Nesting, color functions (oklch, lab), cascade layers, custom media queries, range syntax for media queries, and more.

**Q: Is there a Rust API?**
A: Yes. Lightning CSS is available as a Rust crate for direct integration into Rust-based build tools.

## Sources
- https://github.com/parcel-bundler/lightningcss
- https://lightningcss.dev

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Source: https://tokrepo.com/en/workflows/asset-63a0ea24
Author: Script Depot