fixed issue #6

frontend/lib/main.dart

@@ -16,7 +16,9 @@ import 'pages/flashcards.dart';
 import 'pages/leaderboard.dart';
 //import 'pages/settings.dart';
 
-void main() {
+void main() async {
+  WidgetsFlutterBinding.ensureInitialized();
+  final isDark = await loadDarkMode();
   runApp(
     MultiProvider(
       providers: [
@@ -24,7 +26,7 @@ void main() {
           create: (_) => QuoteProvider()
         ),
         ChangeNotifierProvider(
-          create: (_) => ThemeProvider()
+          create: (_) => ThemeProvider(isDark: isDark)
         )
       ],
       child: HlaskovnikFrontendApp()

frontend/lib/pages/list.dart

@@ -286,21 +286,22 @@ class ListPage extends StatelessWidget {
                 ),
                 ListTile(
                   title: Text(Strings.userPrefersDarkMode),
-                  onTap: () { themeProvider.setDarkMode(!themeProvider.isDark); },
-                  trailing: Row(
-                    mainAxisSize: MainAxisSize.min,
-                    children: [
-                      Padding(
-                        padding: const EdgeInsets.only(right: Constants.edgeInset),
-                        child: Switch(
-                          onChanged: (value) {
-                            themeProvider.setDarkMode(value);
-                          }, 
-                          value: themeProvider.isDark
+                  trailing: Consumer<ThemeProvider>(
+                    builder: (context, themeProvider, _) => Row(
+                      mainAxisSize: MainAxisSize.min,
+                      children: [
+                        Padding(
+                          padding: const EdgeInsets.only(right: Constants.edgeInset),
+                          child: Switch(
+                            onChanged: (value) {
+                              themeProvider.setDarkMode(value);
+                            },
+                            value: themeProvider.isDark,
+                          ),
                         ),
-                      ),
-                      Icon(Icons.dark_mode),
-                    ],
+                        Icon(Icons.dark_mode),
+                      ],
+                    ),
                   ),
                 ),
               ],

frontend/lib/provider/theme_provider.dart

@@ -13,22 +13,16 @@ Future<bool> loadDarkMode() async {
 }
 
 class ThemeProvider extends ChangeNotifier {
-  bool _isDark = false;
+  bool _isDark;
 
   bool get isDark => _isDark;
 
-  ThemeProvider() {
-    _load(); // load saved value on startup
-  }
+  ThemeProvider({required bool isDark}) : _isDark = isDark;
 
-  void _load() async {
-    _isDark = await loadDarkMode();
-    notifyListeners();
-  }
-
-  void setDarkMode(bool value) async {
+  void setDarkMode(bool value) {
+    if (_isDark == value) return; // avoid unnecessary rebuilds
     _isDark = value;
     notifyListeners();
-    await saveDarkMode(value);
+    saveDarkMode(value);
   }
 }