# useBodyClass

Adds one or more CSS classes to `document.body` while the component is mounted, and removes them on unmount.

## Signature

```ts
function useBodyClass(className: string): void;
```

| Parameter   | Type     | Description                                             |
| ----------- | -------- | ------------------------------------------------------- |
| `className` | `string` | Space-separated class name(s) to add to `document.body` |

## Usage

```tsx
export function ModalLayout({ children }: { children: React.ReactNode }) {
  useBodyClass('overflow-hidden bg-overlay');

  return <div>{children}</div>;
}
```

While `ModalLayout` is mounted, `document.body` will have the classes `overflow-hidden` and `bg-overlay`. Both are removed automatically when the component unmounts.

## Notes

- Accepts a space-separated string — multiple classes are handled individually so partial removal is safe.
- Re-applies classes if the `className` prop changes.
- Client-only (`'use client'`). Does not run during SSR.