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

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.light().copyWith(
        navigationRailTheme: const NavigationRailThemeData(
          selectedIconTheme: IconThemeData(
            size: 36.0,
            color: Colors.red,
          ),
          selectedLabelTextStyle: TextStyle(
            fontSize: 20,
            color: Colors.black,
          ),
          unselectedLabelTextStyle: TextStyle(
            fontSize: 16,
            color: Colors.black,
          ),
        ),
      ),
      home: const MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  /// Creates a const [MyHomePage].
  const MyHomePage({super.key});

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _selectedTab = 0;

  @override
  Widget build(BuildContext context) {
    // Define the children to display within the body at different breakpoints.
    final List<Widget> children = <Widget>[
      for (int i = 0; i < 10; i++)
        Padding(
          padding: const EdgeInsets.all(8.0),
          child: Container(
            color: Colors.grey,
            height: 400,
          ),
        )
    ];

    return AdaptiveScaffold(
      useDrawer: false,
      selectedIndex: _selectedTab,
      onSelectedIndexChange: (int index) {
        setState(() => _selectedTab = index);
      },
      destinations: const <NavigationDestination>[
        NavigationDestination(
          icon: Icon(Icons.inbox_outlined),
          label: 'Inbox',
        ),
        NavigationDestination(
          icon: Icon(Icons.article_outlined),
          label: 'Articles',
        ),
        NavigationDestination(
          icon: Icon(Icons.chat_outlined),
          label: 'Chat',
        ),
        NavigationDestination(
          icon: Icon(Icons.video_call_outlined),
          label: 'Video',
        ),
      ],
      body: (_) => GridView.count(crossAxisCount: 2, children: children),
      smallBody: (_) => ListView.builder(
        itemCount: children.length,
        itemBuilder: (_, int idx) => children[idx],
      ),
      // Define a default secondaryBody.
      secondaryBody: (_) => Container(
        color: Colors.pink[200],
      ),
      // Override the default secondaryBody during the smallBreakpoint to be
      // empty. Must use AdaptiveScaffold.emptyBuilder to ensure it is properly
      // overridden.
      smallSecondaryBody: AdaptiveScaffold.emptyBuilder,
    );
  }
}