> For AI agents: the complete documentation index is available at /llms.txt, the full documentation bundle is available at /llms-full.txt.

# tools.cssLoader

- **Type:** `Object | Function`
- **Default:**

```js
const defaultOptions = {
  modules: rsbuildConfig.output.cssModules,
  sourceMap: rsbuildConfig.output.sourceMap.css,
};
```

The config of [css-loader](https://github.com/webpack-contrib/css-loader) can be modified through `tools.cssLoader`.

:::info
The usage of this configuration item is exactly the same as that of Rsbuild. For detailed information, please refer to [Rsbuild - tools.cssLoader](https://v2.rsbuild.dev/config/tools/css-loader).
:::