import 'package:flutter/material.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key? key, required this.title}) : super(key: key);
  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title, style: TextStyle(fontFamily: 'ProductSans')),
      ),
      body: Center(
        child: Text(
          'foo.',
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          Navigator.push(
            context,
            MaterialPageRoute(builder: (context) => secondRoute()),
          );
        },
      ),
    );
  }

  Widget secondRoute() {
    return Scaffold(
      body: Stack(children: [
        CustomScrollView(
          slivers: [
            SliverAppBar(actions: []),
            SliverToBoxAdapter(
              child: Text(' tippy'),
            ),
            SliverToBoxAdapter(
              child: Text(' second'),
            ),
            SliverToBoxAdapter(
              child: Text(' third'),
            ),
            const SliverToBoxAdapter(
              child: SizedBox(
                height: 20,
                child: Center(
                  child: Text('Scroll to see the SliverAppBar in effect.'),
                ),
              ),
            ),
            SliverSafeArea(
              sliver: SliverList(
                delegate: SliverChildBuilderDelegate(
                  (BuildContext context, int index) {
                    return Container(
                      color: index.isOdd ? Colors.white : Colors.black12,
                      height: 100.0,
                      child: Center(
                        child: Text('$index',
                            textScaler: const TextScaler.linear(5)),
                      ),
                    );
                  },
                  childCount: 20,
                ),
              ),
            ),
          ],
        ),
      ]),
    );
  }
}