# useViewport

Returns the current viewport dimensions `[height, width]` and updates them on window resize.

## Signature

```ts
function useViewport(): [number, number];
```

Returns a tuple `[height, width]` in pixels.

## Usage

```tsx
function ResponsiveCanvas() {
  const [height, width] = useViewport();

  return <canvas height={height} width={width} />;
}
```

```tsx
// Destructure with descriptive names
const [viewportHeight, viewportWidth] = useViewport();
```

## Notes

- Reads `window.innerHeight` and `window.innerWidth` — includes the scrollbar area.
- Initialized from the current window size, so there is no flash to `[0, 0]`.
- Client-only (`'use client'`). Will throw during SSR if accessed before mount — pair with `useMounted` if SSR is a concern.