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

# tools.autoprefixer

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

```js
{
  flexbox: 'no-2009',
  // Depends on the browserslist config in the project
  // and the `output.overrideBrowserslist` (higher priority) config
  overrideBrowserslist: browserslist,
}
```

You can modify the config of [autoprefixer](https://github.com/postcss/autoprefixer) by `tools.autoprefixer`.

### Object Type

When `tools.autoprefixer` is configured as `Object` type, it is merged with the default config through Object.assign. For example:

```js
export default {
  tools: {
    autoprefixer: {
      flexbox: 'no-2009',
    },
  },
};
```

### Function Type

When `tools.autoprefixer` is a Function, the default config is passed as the first parameter and can be directly modified or returned as the final result. For example:

```js
export default {
  tools: {
    autoprefixer(config) {
      // modify flexbox config
      config.flexbox = 'no-2009';
    },
  },
};
```