Sharing dart code

main.dart

import 'package:flutter/material.dart';

class MainScreen extends StatefulWidget {
  const MainScreen();

  @override
  _MainScreenState createState() => _MainScreenState();
}

class _MainScreenState extends State<MainScreen> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      body: LayoutBuilder(
        builder: (BuildContext context, BoxConstraints viewportConstraints) {
          return SingleChildScrollView(
            child: ConstrainedBox(
              constraints: BoxConstraints(
                minHeight: viewportConstraints.maxHeight,
              ),
              child: IntrinsicHeight(
                child: Padding(
                  padding: EdgeInsets.all(15),
                  child: Column(
                    children: <Widget>[
                      Expanded(
                        child: Center(
                          child: Container(
                            color: const Color(0xffeeee00),
                            child: Column(
                              mainAxisSize: MainAxisSize.min,
                              children: [
                                const TextField(
                                  obscureText: true,
                                  decoration: InputDecoration(
                                    border: OutlineInputBorder(),
                                    labelText: 'Username',
                                  ),
                                ),
                                const TextField(
                                  obscureText: true,
                                  decoration: InputDecoration(
                                    border: OutlineInputBorder(),
                                    labelText: 'Password',
                                  ),
                                ),
                                TextButton(
                                  style: ButtonStyle(
                                    foregroundColor:
                                        MaterialStateProperty.all<Color>(
                                            Colors.blue),
                                  ),
                                  onPressed: () {},
                                  child: const Text('Login'),
                                ),
                              ],
                            ),
                          ),
                        ),
                      ),
                      Container(
                        color: const Color(0xff008000),
                        alignment: Alignment.center,
                        child: Column(
                          children: [
                            TextButton(
                              style: ButtonStyle(
                                foregroundColor:
                                    MaterialStateProperty.all<Color>(
                                        Colors.white),
                                backgroundColor:
                                    MaterialStateProperty.all<Color>(
                                        Colors.blue),
                              ),
                              onPressed: () {},
                              child: const Text('Bottom Button 1'),
                            ),
                            TextButton(
                              style: ButtonStyle(
                                foregroundColor:
                                    MaterialStateProperty.all<Color>(
                                        Colors.white),
                                backgroundColor:
                                    MaterialStateProperty.all<Color>(
                                        Colors.blue),
                              ),
                              onPressed: () {},
                              child: const Text('Bottom Button 2'),
                            )
                          ],
                        ),
                      ),
                    ],
                  ),
                ),
              ),
            ),
          );
        },
      ),
    );
  }
}