import 'package:flutter/material.dart';

// wrap your LoginPage widget with a MaterialApp widget
void main() => runApp(MaterialApp(home:LoginPage()));

class LoginPage extends StatelessWidget{

  @override
  Widget build(BuildContext context){
    return MaterialApp(
      home: Scaffold(
        body: Container(
          constraints: BoxConstraints.expand(),
          child: Column(
            mainAxisAlignment: MainAxisAlignment.start,
            children: [
              Container(
                color: Colors.red,
                width: double.infinity,
                height: MediaQuery.of(context).size.height/3,
              )
            ],
          )
        )
      )
    );
  }
}