themeextension ex

snippet.dart

Widget build(BuildContext context){
    final light = ColorScheme.fromSeed(dynamicSchemeVariant: DynamicSchemeVariant.tonalSpot,
        contrastLevel: 0.1,
        seedColor: Colors.purple, brightness: Brightness.light).toM3EThemeData();
    final dark = ColorScheme.fromSeed(dynamicSchemeVariant: DynamicSchemeVariant.tonalSpot,
        contrastLevel: 0.1,
        seedColor: Colors.purple, brightness: Brightness.dark).toM3EThemeData();
    return MaterialApp(
       title: "Me".
       theme: light.toM3ETheme(),
       darkTheme: dark.toM3ETheme(),
       themeMode: ThemeMode.system,
       home: Child(),
       debugShowCheckedModeBanner: false,
     );
  }