Rectangle App

main.dart

import 'package:flutter/material.dart';

void main() => runApp(MaterialApp(
      title: "Hello Rectangle",
      home: Scaffold(
        appBar: AppBar(
          title: Text("Rectangle App"),
        ),
        body: RectangleApp(),
      ),
    ));

class RectangleApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Center(
      child: Container(
        height: 400.0,
        width: 300.0,
        color: Colors.greenAccent,
        child: Center(
          child: Text(
            "Hello Rectangle",
            textAlign: TextAlign.center,
            style: TextStyle(
              color: Colors.purple,
              fontSize: 30,
            ),
          ),
        ),
      ),
    );
  }
}