theme extension example

snippet.dart

Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData(
        extensions: const <ThemeExtension<dynamic>>[
          MyColors(brandColor: Color(0xFF1E88E5), danger: Color(0xFFE53935)),
        ],
      ),
      darkTheme: ThemeData.dark().copyWith(
        extensions: <ThemeExtension<dynamic>>[
          const MyColors(brandColor: Color(0xFF90CAF9), danger: Color(0xFFEF9A9A)),
        ],
      ),
      themeMode: isLightTheme ? ThemeMode.light : ThemeMode.dark,
      home: Home(isLightTheme: isLightTheme, toggleTheme: toggleTheme),
    );
  }