Dark theme

diff --git a/lib/l10n/app_en.arb b/lib/l10n/app_en.arb
index ecbac48..8e73a9f 100644
--- a/lib/l10n/app_en.arb
+++ b/lib/l10n/app_en.arb
@@ -79,6 +79,10 @@
   "settingsAppLockUnableToAuthError": "Unable to authenticate.",
   "settingsVerboseLoggingLabel": "Verbose Logging",
   "settingsVerboseLoggingDescription": "Logs wallet operations to a text file in the app's data folder for debugging purposes.",
+  "settingsThemeLabel": "Theme",
+  "settingsThemeSystem": "System",
+  "settingsThemeLight": "Light",
+  "settingsThemeDark": "Dark",
   "settingsLanguageLabel": "Language",
   "settingsDisplayCurrencyLabel": "Display Currency",
   "settingsLwsViewKeysLabel": "LWS View Keys",
diff --git a/lib/l10n/app_localizations.dart b/lib/l10n/app_localizations.dart
index d0e9118..2e97fd8 100644
--- a/lib/l10n/app_localizations.dart
+++ b/lib/l10n/app_localizations.dart
@@ -572,6 +572,30 @@ abstract class AppLocalizations {
   /// **'Logs wallet operations to a text file in the app\'s data folder for debugging purposes.'**
   String get settingsVerboseLoggingDescription;
 
+  /// No description provided for @settingsThemeLabel.
+  ///
+  /// In en, this message translates to:
+  /// **'Theme'**
+  String get settingsThemeLabel;
+
+  /// No description provided for @settingsThemeSystem.
+  ///
+  /// In en, this message translates to:
+  /// **'System'**
+  String get settingsThemeSystem;
+
+  /// No description provided for @settingsThemeLight.
+  ///
+  /// In en, this message translates to:
+  /// **'Light'**
+  String get settingsThemeLight;
+
+  /// No description provided for @settingsThemeDark.
+  ///
+  /// In en, this message translates to:
+  /// **'Dark'**
+  String get settingsThemeDark;
+
   /// No description provided for @settingsLanguageLabel.
   ///
   /// In en, this message translates to:
diff --git a/lib/l10n/app_localizations_en.dart b/lib/l10n/app_localizations_en.dart
index 45e9526..ff0a3d3 100644
--- a/lib/l10n/app_localizations_en.dart
+++ b/lib/l10n/app_localizations_en.dart
@@ -258,6 +258,18 @@ class AppLocalizationsEn extends AppLocalizations {
   String get settingsVerboseLoggingDescription =>
       'Logs wallet operations to a text file in the app\'s data folder for debugging purposes.';
 
+  @override
+  String get settingsThemeLabel => 'Theme';
+
+  @override
+  String get settingsThemeSystem => 'System';
+
+  @override
+  String get settingsThemeLight => 'Light';
+
+  @override
+  String get settingsThemeDark => 'Dark';
+
   @override
   String get settingsLanguageLabel => 'Language';
 
diff --git a/lib/l10n/app_localizations_pt.dart b/lib/l10n/app_localizations_pt.dart
index db4b2c7..96d34c2 100644
--- a/lib/l10n/app_localizations_pt.dart
+++ b/lib/l10n/app_localizations_pt.dart
@@ -258,6 +258,18 @@ class AppLocalizationsPt extends AppLocalizations {
   String get settingsVerboseLoggingDescription =>
       'Registra operações da carteira em um arquivo de texto na pasta de dados do app para fins de depuração.';
 
+  @override
+  String get settingsThemeLabel => 'Tema';
+
+  @override
+  String get settingsThemeSystem => 'Sistema';
+
+  @override
+  String get settingsThemeLight => 'Claro';
+
+  @override
+  String get settingsThemeDark => 'Escuro';
+
   @override
   String get settingsLanguageLabel => 'Idioma';
 
diff --git a/lib/l10n/app_pt.arb b/lib/l10n/app_pt.arb
index d788e0e..3b35b00 100644
--- a/lib/l10n/app_pt.arb
+++ b/lib/l10n/app_pt.arb
@@ -79,6 +79,10 @@
   "settingsAppLockUnableToAuthError": "Não foi possível autenticar.",
   "settingsVerboseLoggingLabel": "Logs Detalhados",
   "settingsVerboseLoggingDescription": "Registra operações da carteira em um arquivo de texto na pasta de dados do app para fins de depuração.",
+  "settingsThemeLabel": "Tema",
+  "settingsThemeSystem": "Sistema",
+  "settingsThemeLight": "Claro",
+  "settingsThemeDark": "Escuro",
   "settingsLanguageLabel": "Idioma",
   "settingsDisplayCurrencyLabel": "Moeda Local",
   "settingsLwsViewKeysLabel": "Chaves de Visualização do LWS",
diff --git a/lib/main.dart b/lib/main.dart
index 1a7e1c9..9357539 100644
--- a/lib/main.dart
+++ b/lib/main.dart
@@ -16,6 +16,7 @@ import 'package:skylight_wallet/screens/scan_qr.dart';
 import 'package:skylight_wallet/screens/secret_keys.dart';
 import 'package:skylight_wallet/services/tor_service.dart';
 import 'package:skylight_wallet/models/language_model.dart';
+import 'package:skylight_wallet/models/theme_model.dart';
 import 'package:skylight_wallet/l10n/app_localizations.dart';
 import 'package:skylight_wallet/screens/settings.dart';
 import 'package:skylight_wallet/models/wallet_model.dart';
@@ -60,18 +61,16 @@ class MyApp extends StatelessWidget {
       providers: [
         ChangeNotifierProvider(create: (context) => WalletModel()),
         ChangeNotifierProvider(create: (context) => LanguageModel()),
+        ChangeNotifierProvider(create: (context) => ThemeModel()),
         ChangeNotifierProvider(create: (context) => FiatRateModel()),
       ],
-      child: Consumer<LanguageModel>(
-        builder: (context, languageProvider, child) {
+      child: Consumer2<LanguageModel, ThemeModel>(
+        builder: (context, languageProvider, themeProvider, child) {
           final wallet = Provider.of<WalletModel>(context, listen: false);
 
           return FutureBuilder(
-            // Since LanguageModel loads the user's language from
-            // SharedPreferences, we need to wait until an instance is loaded.
-            // We also need to wait until it is determined whether or not a
-            // wallet already exists, so we know which screen to send the user
-            // to initially.
+            // We need to check for wallet existence to determine the correct initial route,
+            // but we'll do this quickly without loading the wallet to avoid startup delay.
             future: Future.wait([
               SharedPreferences.getInstance(),
               loadExistingWalletIfExists(wallet),
@@ -83,6 +82,10 @@ class MyApp extends StatelessWidget {
                     snapshot.data![0] as SharedPreferences;
                 final walletExists = snapshot.data![1] as bool;
 
+                final theme =
+                    sharedPreferences.getString(SharedPreferencesKeys.theme) ??
+                    'system';
+
                 final appLockEnabled =
                     sharedPreferences.getBool(
                       SharedPreferencesKeys.appLockEnabled,
@@ -111,6 +114,17 @@ class MyApp extends StatelessWidget {
                   theme: ThemeData(
                     colorScheme: ColorScheme.fromSeed(seedColor: Colors.blue),
                   ),
+                  darkTheme: ThemeData(
+                    colorScheme: ColorScheme.fromSeed(
+                      seedColor: Colors.blue,
+                      brightness: Brightness.dark,
+                    ),
+                  ),
+                  themeMode: theme == 'dark'
+                      ? ThemeMode.dark
+                      : theme == 'light'
+                      ? ThemeMode.light
+                      : ThemeMode.system,
                   initialRoute: initialRoute,
                   locale: Locale.fromSubtags(
                     languageCode: languageProvider.language,
@@ -149,6 +163,13 @@ class MyApp extends StatelessWidget {
                 theme: ThemeData(
                   colorScheme: ColorScheme.fromSeed(seedColor: Colors.blue),
                 ),
+                darkTheme: ThemeData(
+                  colorScheme: ColorScheme.fromSeed(
+                    seedColor: Colors.blue,
+                    brightness: Brightness.dark,
+                  ),
+                ),
+                themeMode: ThemeMode.system,
                 builder: (context, child) => Scaffold(),
               );
             },
diff --git a/lib/models/theme_model.dart b/lib/models/theme_model.dart
new file mode 100644
index 0000000..2efc4d2
--- /dev/null
+++ b/lib/models/theme_model.dart
@@ -0,0 +1,48 @@
+import 'package:flutter/material.dart';
+import 'package:skylight_wallet/services/shared_preferences_service.dart';
+
+class ThemeModel with ChangeNotifier {
+  String _theme = 'system';
+
+  String get theme => _theme;
+
+  ThemeModel() {
+    _loadTheme();
+  }
+
+  Future<void> _loadTheme() async {
+    final String? preferencesTheme = await SharedPreferencesService.get<String>(
+      SharedPreferencesKeys.theme,
+    );
+
+    if (preferencesTheme != null) {
+      _theme = preferencesTheme;
+    }
+    notifyListeners();
+  }
+
+  void setTheme(String? newTheme) async {
+    if (newTheme == null) return;
+
+    _theme = newTheme;
+
+    await SharedPreferencesService.set<String>(
+      SharedPreferencesKeys.theme,
+      newTheme,
+    );
+
+    notifyListeners();
+  }
+
+  ThemeMode get themeMode {
+    switch (_theme) {
+      case 'light':
+        return ThemeMode.light;
+      case 'dark':
+        return ThemeMode.dark;
+      case 'system':
+      default:
+        return ThemeMode.system;
+    }
+  }
+}
diff --git a/lib/screens/receive.dart b/lib/screens/receive.dart
index 27868a9..cf69e08 100644
--- a/lib/screens/receive.dart
+++ b/lib/screens/receive.dart
@@ -84,6 +84,8 @@ class _ReceiveScreenState extends State<ReceiveScreen> {
   @override
   Widget build(BuildContext context) {
     final i18n = AppLocalizations.of(context)!;
+    final brightness = Theme.of(context).brightness;
+    final isDarkTheme = brightness == Brightness.dark;
 
     return Scaffold(
       appBar: AppBar(title: Text(i18n.receiveTitle)),
@@ -94,7 +96,17 @@ class _ReceiveScreenState extends State<ReceiveScreen> {
             mainAxisAlignment: MainAxisAlignment.center,
             spacing: 20,
             children: [
-              QrImageView(data: _address),
+              QrImageView(
+                data: _address,
+                eyeStyle: QrEyeStyle(
+                  eyeShape: QrEyeShape.square,
+                  color: isDarkTheme ? Colors.grey[300] : Colors.black,
+                ),
+                dataModuleStyle: QrDataModuleStyle(
+                  dataModuleShape: QrDataModuleShape.square,
+                  color: isDarkTheme ? Colors.grey[300] : Colors.black,
+                ),
+              ),
               if (_showSubaddress)
                 Text(
                   i18n.receiveSubaddressWarn,
diff --git a/lib/screens/settings.dart b/lib/screens/settings.dart
index 0f26e85..7232df1 100644
--- a/lib/screens/settings.dart
+++ b/lib/screens/settings.dart
@@ -7,6 +7,7 @@ import 'package:skylight_wallet/consts.dart';
 import 'package:skylight_wallet/l10n/app_localizations.dart';
 import 'package:skylight_wallet/models/fiat_rate_model.dart';
 import 'package:skylight_wallet/models/language_model.dart';
+import 'package:skylight_wallet/models/theme_model.dart';
 import 'package:skylight_wallet/models/wallet_model.dart';
 import 'package:skylight_wallet/periodic_tasks.dart';
 import 'package:skylight_wallet/services/notifications_service.dart';
@@ -287,6 +288,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
   Widget build(BuildContext context) {
     final i18n = AppLocalizations.of(context)!;
     final language = context.watch<LanguageModel>();
+    final theme = context.watch<ThemeModel>();
 
     return Scaffold(
       bottomNavigationBar: WalletNavigationBar(selectedIndex: 1),
@@ -299,23 +301,27 @@ class _SettingsScreenState extends State<SettingsScreen> {
             Row(
               mainAxisAlignment: MainAxisAlignment.spaceBetween,
               children: [
-                Text(
-                  i18n.settingsNotifyNewTxsLabel,
-                  style: TextStyle(fontSize: 18),
-                ),
-                Switch(
-                  value: _newTxNotificationsEnabled,
-                  onChanged: _setTxNotificationsEnabled,
+                Text(i18n.settingsThemeLabel, style: TextStyle(fontSize: 18)),
+                DropdownButton<String>(
+                  value: theme.theme,
+                  onChanged: theme.setTheme,
+                  items: [
+                    DropdownMenuItem<String>(
+                      value: 'system',
+                      child: Text(i18n.settingsThemeSystem),
+                    ),
+                    DropdownMenuItem<String>(
+                      value: 'light',
+                      child: Text(i18n.settingsThemeLight),
+                    ),
+                    DropdownMenuItem<String>(
+                      value: 'dark',
+                      child: Text(i18n.settingsThemeDark),
+                    ),
+                  ],
                 ),
               ],
             ),
-            Row(
-              mainAxisAlignment: MainAxisAlignment.spaceBetween,
-              children: [
-                Text(i18n.settingsAppLockLabel, style: TextStyle(fontSize: 18)),
-                Switch(value: _appLockEnabled, onChanged: _setAppLockEnabled),
-              ],
-            ),
             Row(
               mainAxisAlignment: MainAxisAlignment.spaceBetween,
               children: [
@@ -354,6 +360,26 @@ class _SettingsScreenState extends State<SettingsScreen> {
                 ),
               ],
             ),
+            Row(
+              mainAxisAlignment: MainAxisAlignment.spaceBetween,
+              children: [
+                Text(i18n.settingsAppLockLabel, style: TextStyle(fontSize: 18)),
+                Switch(value: _appLockEnabled, onChanged: _setAppLockEnabled),
+              ],
+            ),
+            Row(
+              mainAxisAlignment: MainAxisAlignment.spaceBetween,
+              children: [
+                Text(
+                  i18n.settingsNotifyNewTxsLabel,
+                  style: TextStyle(fontSize: 18),
+                ),
+                Switch(
+                  value: _newTxNotificationsEnabled,
+                  onChanged: _setTxNotificationsEnabled,
+                ),
+              ],
+            ),
             Row(
               mainAxisAlignment: MainAxisAlignment.spaceBetween,
               children: [
@@ -367,7 +393,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
                       ),
                       Text(
                         i18n.settingsVerboseLoggingDescription,
-                        style: TextStyle(fontSize: 13, color: Colors.grey[600]),
+                        style: TextStyle(fontSize: 12, color: Colors.grey[600]),
                       ),
                     ],
                   ),
diff --git a/lib/services/shared_preferences_service.dart b/lib/services/shared_preferences_service.dart
index b19b75c..4509a27 100644
--- a/lib/services/shared_preferences_service.dart
+++ b/lib/services/shared_preferences_service.dart
@@ -4,6 +4,7 @@ class SharedPreferencesKeys {
   static const String language = 'language';
   static const String fiatCurrency = 'fiatCurrency';
   static const String fiatRate = 'fiatRate';
+  static const String theme = 'theme';
   static const String notificationsEnabled = 'notificationsEnabled';
   static const String appLockEnabled = 'appLockEnabled';
   static const String verboseLoggingEnabled = 'verboseLoggingEnabled';
diff --git a/lib/widgets/status_icon.dart b/lib/widgets/status_icon.dart
index 2cedbe8..9e38445 100644
--- a/lib/widgets/status_icon.dart
+++ b/lib/widgets/status_icon.dart
@@ -3,13 +3,16 @@ import 'package:flutter/material.dart';
 enum StatusIconStatus { loading, complete, fail }
 
 class StatusIcon extends StatelessWidget {
+  const StatusIcon({super.key, required this.child, required this.status});
+
   final Widget child;
   final StatusIconStatus status;
 
-  const StatusIcon({super.key, required this.child, required this.status});
-
   @override
   Widget build(BuildContext context) {
+    final brightness = Theme.of(context).brightness;
+    final isDarkTheme = brightness == Brightness.dark;
+
     return SizedBox(
       width: 22,
       height: 22,
@@ -24,7 +27,7 @@ class StatusIcon extends StatelessWidget {
               width: 12,
               height: 12,
               decoration: BoxDecoration(
-                color: Colors.white,
+                color: isDarkTheme ? Colors.grey[900] : Colors.white,
                 shape: BoxShape.circle,
               ),
               child: status == StatusIconStatus.complete