Widget build(BuildContext context) {
    return Scaffold(
      body: ConstrainedBox(
          constraints: BoxConstraints.expand(height: 200),
          child: Container(
            height: 400,
            color: Colors.blue,
            child: Center(
              child: Padding(
                  padding: EdgeInsets.all(16),
                  child: Text(
                    'Box Constraint',
                    style: TextStyle(color: Colors.white),
                  )),
            ),
          )),
    );
  }