diff --git a/lib/main.dart b/lib/main.dart
index 828f71e..7f5283b 100644
--- a/lib/main.dart
+++ b/lib/main.dart
@@ -1,5 +1,4 @@
 import 'package:flutter/material.dart';
-import 'package:flutter/services.dart';
 import 'package:traccar_client/main_screen.dart';
 import 'package:traccar_client/permission_screen.dart';
 import 'package:traccar_client/preferences.dart';
diff --git a/lib/main_screen.dart b/lib/main_screen.dart
index a9bacd9..6d48451 100644
--- a/lib/main_screen.dart
+++ b/lib/main_screen.dart
@@ -188,7 +188,7 @@ class _MainScreenState extends State<MainScreen> with TickerProviderStateMixin {
               boxShadow: _isTracking
                   ? [
                       BoxShadow(
-                        color: const Color(0xFF00e676).withOpacity(0.6),
+                        color: const Color(0xFF00e676).withValues(alpha: 0.6),
                         blurRadius: 8,
                         spreadRadius: 2,
                       ),
@@ -248,7 +248,7 @@ class _MainScreenState extends State<MainScreen> with TickerProviderStateMixin {
                   fontSize: 11,
                   fontWeight: FontWeight.w700,
                   letterSpacing: 2,
-                  color: const Color(0xFF00bcd4).withOpacity(0.8),
+                  color: const Color(0xFF00bcd4).withValues(alpha: 0.8),
                 ),
               ),
             ],
@@ -330,7 +330,7 @@ class _MainScreenState extends State<MainScreen> with TickerProviderStateMixin {
                       BoxShadow(
                         color: const Color(
                           0xFF00e676,
-                        ).withOpacity(0.15 * _pulseAnimation.value),
+                        ).withValues(alpha: 0.15 * _pulseAnimation.value),
                         blurRadius: 12,
                         spreadRadius: 0,
                       ),
diff --git a/lib/permission_screen.dart b/lib/permission_screen.dart
index d5de06b..d2b1b97 100644
--- a/lib/permission_screen.dart
+++ b/lib/permission_screen.dart
@@ -324,7 +324,7 @@ class _PermissionScreenState extends State<PermissionScreen> {
             borderRadius: BorderRadius.circular(4),
             border: Border.all(
               color: granted
-                  ? const Color(0xFF00e676).withOpacity(0.3)
+                  ? const Color(0xFF00e676).withValues(alpha: 0.3)
                   : const Color(0xFF2a2a2a),
               width: 1,
             ),
@@ -336,7 +336,7 @@ class _PermissionScreenState extends State<PermissionScreen> {
                 height: 36,
                 decoration: BoxDecoration(
                   color: granted
-                      ? const Color(0xFF00e676).withOpacity(0.15)
+                      ? const Color(0xFF00e676).withValues(alpha: 0.15)
                       : const Color(0xFF2a2a2a),
                   borderRadius: BorderRadius.circular(4),
                 ),
@@ -382,10 +382,10 @@ class _PermissionScreenState extends State<PermissionScreen> {
                     vertical: 4,
                   ),
                   decoration: BoxDecoration(
-                    color: const Color(0xFF00e676).withOpacity(0.15),
+                    color: const Color(0xFF00e676).withValues(alpha: 0.15),
                     borderRadius: BorderRadius.circular(3),
                     border: Border.all(
-                      color: const Color(0xFF00e676).withOpacity(0.4),
+                      color: const Color(0xFF00e676).withValues(alpha: 0.4),
                       width: 1,
                     ),
                   ),
@@ -407,10 +407,10 @@ class _PermissionScreenState extends State<PermissionScreen> {
                     vertical: 4,
                   ),
                   decoration: BoxDecoration(
-                    color: const Color(0xFF00bcd4).withOpacity(0.1),
+                    color: const Color(0xFF00bcd4).withValues(alpha: 0.1),
                     borderRadius: BorderRadius.circular(3),
                     border: Border.all(
-                      color: const Color(0xFF00bcd4).withOpacity(0.4),
+                      color: const Color(0xFF00bcd4).withValues(alpha: 0.4),
                       width: 1,
                     ),
                   ),
@@ -491,7 +491,7 @@ class _PermissionScreenState extends State<PermissionScreen> {
   Widget _buildContinueButton() {
     return Material(
       color: _allGranted
-          ? const Color(0xFF00e676).withOpacity(0.15)
+          ? const Color(0xFF00e676).withValues(alpha: 0.15)
           : const Color(0xFF2a2a2a),
       borderRadius: BorderRadius.circular(4),
       child: InkWell(
@@ -504,7 +504,7 @@ class _PermissionScreenState extends State<PermissionScreen> {
             borderRadius: BorderRadius.circular(4),
             border: Border.all(
               color: _allGranted
-                  ? const Color(0xFF00e676).withOpacity(0.4)
+                  ? const Color(0xFF00e676).withValues(alpha: 0.4)
                   : const Color(0xFF2a2a2a),
               width: 1,
             ),
diff --git a/lib/settings_screen.dart b/lib/settings_screen.dart
index b43983f..b2e0187 100644
--- a/lib/settings_screen.dart
+++ b/lib/settings_screen.dart
@@ -240,7 +240,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
         border: Border.all(color: const Color(0xFF2a2a2a), width: 1),
       ),
       child: DropdownButtonFormField<int>(
-        value: _accuracy,
+        initialValue: _accuracy,
         dropdownColor: const Color(0xFF1a1a1a),
         style: const TextStyle(
           fontFamily: 'monospace',
@@ -359,8 +359,8 @@ class _SettingsScreenState extends State<SettingsScreen> {
           Switch(
             value: value,
             onChanged: onChanged,
-            activeColor: const Color(0xFF00e676),
-            activeTrackColor: const Color(0xFF00e676).withOpacity(0.3),
+            activeThumbColor: const Color(0xFF00e676),
+            activeTrackColor: const Color(0xFF00e676).withValues(alpha: 0.3),
           ),
         ],
       ),
@@ -369,7 +369,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
 
   Widget _buildSaveButton() {
     return Material(
-      color: const Color(0xFF00bcd4).withOpacity(0.1),
+      color: const Color(0xFF00bcd4).withValues(alpha: 0.1),
       borderRadius: BorderRadius.circular(4),
       child: InkWell(
         onTap: _saveSettings,
@@ -380,7 +380,7 @@ class _SettingsScreenState extends State<SettingsScreen> {
           decoration: BoxDecoration(
             borderRadius: BorderRadius.circular(4),
             border: Border.all(
-              color: const Color(0xFF00bcd4).withOpacity(0.4),
+              color: const Color(0xFF00bcd4).withValues(alpha: 0.4),
               width: 1,
             ),
           ),
diff --git a/lib/status_screen.dart b/lib/status_screen.dart
index 9dd2a0a..87b3d98 100644
--- a/lib/status_screen.dart
+++ b/lib/status_screen.dart
@@ -189,7 +189,9 @@ class _StatusScreenState extends State<StatusScreen> {
                           style: TextStyle(
                             fontFamily: 'monospace',
                             fontSize: 11,
-                            color: const Color(0xFF424242).withOpacity(0.6),
+                            color: const Color(
+                              0xFF424242,
+                            ).withValues(alpha: 0.6),
                           ),
                         ),
                       ],
@@ -217,12 +219,12 @@ class _StatusScreenState extends State<StatusScreen> {
         padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 4),
         decoration: BoxDecoration(
           color: isSelected
-              ? const Color(0xFF00bcd4).withOpacity(0.15)
+              ? const Color(0xFF00bcd4).withValues(alpha: 0.15)
               : Colors.transparent,
           borderRadius: BorderRadius.circular(3),
           border: Border.all(
             color: isSelected
-                ? const Color(0xFF00bcd4).withOpacity(0.5)
+                ? const Color(0xFF00bcd4).withValues(alpha: 0.5)
                 : const Color(0xFF2a2a2a),
             width: 1,
           ),
@@ -276,7 +278,7 @@ class _StatusScreenState extends State<StatusScreen> {
                 width: 16,
                 height: 16,
                 decoration: BoxDecoration(
-                  color: color.withOpacity(0.15),
+                  color: color.withValues(alpha: 0.15),
                   borderRadius: BorderRadius.circular(3),
                 ),
                 child: Icon(icon, size: 10, color: color),
@@ -285,7 +287,7 @@ class _StatusScreenState extends State<StatusScreen> {
               Container(
                 padding: const EdgeInsets.symmetric(horizontal: 5, vertical: 1),
                 decoration: BoxDecoration(
-                  color: color.withOpacity(0.1),
+                  color: color.withValues(alpha: 0.1),
                   borderRadius: BorderRadius.circular(2),
                 ),
                 child: Text(