Widget build(BuildContext context) {
    return Scaffold(
      body: ConstrainedBox(
          constraints: BoxConstraints.tight(Size(150, 200)),
          child: Center(
            child: Container(
              color: Colors.blue,
              child: Padding(
                  padding: EdgeInsets.all(16),
                  child: Text(
                    'Box Constraints',
                    style: TextStyle(color: Colors.orange),
                  )),
            ),
          )),
    );
  }