A very simple flutter widget!

main.dart

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return CupertinoApp(
      home: Container(
        color: Colors.amber,
        child: Center(
            child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: <Widget>[
            Text(
              "What's Flutter?",
              style: TextStyle(fontSize: 30),
            ),
            Padding(
              padding: const EdgeInsets.all(30.0),
              child: Text(
                "Flutter is Google’s UI toolkit for building beautiful, natively compiled applications for mobile, web, and desktop from a single codebase.",
                style: TextStyle(fontSize: 20),
                textAlign: TextAlign.center,
              ),
            ),
          ],
        )),
      ),
    );
  }
}