This is a great library, however it is missing a way to attach a ref to Box's underlying DOM node. This is useful for integrations with other third party libraries.

Specifically we want to be able to integrate with react-beautiful-dnd, which requires an exposed ref on the draggable items.

Would you be open to a PR that introduces an elementRef prop to the Box component?

Example usage:

render() {
  return (
    <Box elementRef={...}>
      {this.props.children}
    </Box>
  );
}