feat: system light/dark theme support with live switching and dark title bar

windows/App.xaml

@@ -3,64 +3,47 @@
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              ShutdownMode="OnExplicitShutdown">
     <Application.Resources>
-        <SolidColorBrush x:Key="BackgroundBrush"    Color="#1C1C1E"/>
-        <SolidColorBrush x:Key="CardBrush"          Color="#2C2C2E"/>
-        <SolidColorBrush x:Key="AccentBrush"        Color="#F97316"/>
-        <SolidColorBrush x:Key="SecondaryBrush"     Color="#888888"/>
-        <SolidColorBrush x:Key="BorderBrush"        Color="#38383A"/>
-        <SolidColorBrush x:Key="BlueBrush"          Color="#3B82F6"/>
+        <SolidColorBrush x:Key="BackgroundBrush"   Color="#F3F3F3"/>
+        <SolidColorBrush x:Key="CardBrush"         Color="#FFFFFF"/>
+        <SolidColorBrush x:Key="AccentBrush"       Color="#F97316"/>
+        <SolidColorBrush x:Key="TextBrush"         Color="#1C1C1C"/>
+        <SolidColorBrush x:Key="SecondaryBrush"    Color="#6E6E6E"/>
+        <SolidColorBrush x:Key="BorderBrush"       Color="#E0E0E0"/>
+        <SolidColorBrush x:Key="BlueBrush"         Color="#0078D4"/>
+        <SolidColorBrush x:Key="ButtonBrush"       Color="#FFFFFF"/>
+        <SolidColorBrush x:Key="SurfaceBrush"      Color="#FAFAFA"/>
+        <SolidColorBrush x:Key="BannerBgBrush"     Color="#E8F2FB"/>
+        <SolidColorBrush x:Key="BannerBorderBrush" Color="#B3D6F5"/>
 
         <Style x:Key="HeaderText" TargetType="TextBlock">
             <Setter Property="FontSize"   Value="10"/>
             <Setter Property="FontWeight" Value="SemiBold"/>
             <Setter Property="Foreground" Value="{StaticResource SecondaryBrush}"/>
-        </Style>
-
-        <Style x:Key="IconButton" TargetType="Button">
-            <Setter Property="Background"  Value="Transparent"/>
-            <Setter Property="BorderBrush" Value="#33FFFFFF"/>
-            <Setter Property="BorderThickness" Value="0.5"/>
-            <Setter Property="Foreground"  Value="{StaticResource SecondaryBrush}"/>
-            <Setter Property="Width"       Value="26"/>
-            <Setter Property="Height"      Value="26"/>
-            <Setter Property="Cursor"      Value="Hand"/>
-            <Setter Property="Template">
-                <Setter.Value>
-                    <ControlTemplate TargetType="Button">
-                        <Border Background="{TemplateBinding Background}"
-                                BorderBrush="{TemplateBinding BorderBrush}"
-                                BorderThickness="{TemplateBinding BorderThickness}"
-                                CornerRadius="5">
-                            <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center"/>
-                        </Border>
-                        <ControlTemplate.Triggers>
-                            <Trigger Property="IsMouseOver" Value="True">
-                                <Setter Property="Background" Value="#1AFFFFFF"/>
-                            </Trigger>
-                        </ControlTemplate.Triggers>
-                    </ControlTemplate>
-                </Setter.Value>
-            </Setter>
+            <Setter Property="FontFamily" Value="Segoe UI"/>
         </Style>
 
         <Style x:Key="PrimaryButton" TargetType="Button">
-            <Setter Property="Background"  Value="{StaticResource BlueBrush}"/>
-            <Setter Property="Foreground"  Value="White"/>
+            <Setter Property="Background"      Value="{StaticResource BlueBrush}"/>
+            <Setter Property="Foreground"      Value="White"/>
             <Setter Property="BorderThickness" Value="0"/>
-            <Setter Property="Padding"     Value="14,6"/>
-            <Setter Property="FontSize"    Value="12"/>
-            <Setter Property="FontWeight"  Value="SemiBold"/>
-            <Setter Property="Cursor"      Value="Hand"/>
+            <Setter Property="Padding"         Value="14,6"/>
+            <Setter Property="FontSize"        Value="12"/>
+            <Setter Property="FontWeight"      Value="SemiBold"/>
+            <Setter Property="FontFamily"      Value="Segoe UI"/>
+            <Setter Property="Cursor"          Value="Hand"/>
             <Setter Property="Template">
                 <Setter.Value>
                     <ControlTemplate TargetType="Button">
-                        <Border Background="{TemplateBinding Background}" CornerRadius="6"
+                        <Border Background="{TemplateBinding Background}" CornerRadius="4"
                                 Padding="{TemplateBinding Padding}">
                             <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center"/>
                         </Border>
                         <ControlTemplate.Triggers>
                             <Trigger Property="IsMouseOver" Value="True">
-                                <Setter Property="Background" Value="#2563EB"/>
+                                <Setter Property="Background" Value="#106EBE"/>
+                            </Trigger>
+                            <Trigger Property="IsEnabled" Value="False">
+                                <Setter Property="Background" Value="#BDBDBD"/>
                             </Trigger>
                         </ControlTemplate.Triggers>
                     </ControlTemplate>
@@ -69,25 +52,26 @@
         </Style>
 
         <Style x:Key="SmallButton" TargetType="Button">
-            <Setter Property="Background"    Value="Transparent"/>
-            <Setter Property="BorderBrush"   Value="#33FFFFFF"/>
-            <Setter Property="BorderThickness" Value="0.5"/>
-            <Setter Property="Foreground"    Value="{StaticResource SecondaryBrush}"/>
-            <Setter Property="Padding"       Value="8,4"/>
-            <Setter Property="FontSize"      Value="11"/>
-            <Setter Property="Cursor"        Value="Hand"/>
+            <Setter Property="Background"      Value="{StaticResource ButtonBrush}"/>
+            <Setter Property="BorderBrush"     Value="{StaticResource BorderBrush}"/>
+            <Setter Property="BorderThickness" Value="1"/>
+            <Setter Property="Foreground"      Value="{StaticResource TextBrush}"/>
+            <Setter Property="Padding"         Value="10,4"/>
+            <Setter Property="FontSize"        Value="12"/>
+            <Setter Property="FontFamily"      Value="Segoe UI"/>
+            <Setter Property="Cursor"          Value="Hand"/>
             <Setter Property="Template">
                 <Setter.Value>
                     <ControlTemplate TargetType="Button">
                         <Border Background="{TemplateBinding Background}"
                                 BorderBrush="{TemplateBinding BorderBrush}"
                                 BorderThickness="{TemplateBinding BorderThickness}"
-                                CornerRadius="5" Padding="{TemplateBinding Padding}">
+                                CornerRadius="4" Padding="{TemplateBinding Padding}">
                             <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center"/>
                         </Border>
                         <ControlTemplate.Triggers>
                             <Trigger Property="IsMouseOver" Value="True">
-                                <Setter Property="Background" Value="#1AFFFFFF"/>
+                                <Setter Property="Background" Value="#F0F0F0"/>
                             </Trigger>
                         </ControlTemplate.Triggers>
                     </ControlTemplate>
@@ -95,8 +79,13 @@
             </Setter>
         </Style>
 
+        <Style TargetType="ComboBox">
+            <Setter Property="FontFamily" Value="Segoe UI"/>
+            <Setter Property="FontSize"   Value="12"/>
+        </Style>
+
         <Style TargetType="ScrollViewer">
-            <Setter Property="VerticalScrollBarVisibility" Value="Hidden"/>
+            <Setter Property="VerticalScrollBarVisibility" Value="Auto"/>
         </Style>
     </Application.Resources>
 </Application>

windows/App.xaml.cs

@@ -18,6 +18,7 @@ public partial class App : Application
     protected override void OnStartup(StartupEventArgs e)
     {
         base.OnStartup(e);
+        ThemeManager.Initialize();
         SetupTray();
         ScheduleTimer(ViewModel.RefreshInterval);
 
@@ -78,21 +79,11 @@ public partial class App : Application
         if (_popup == null)
         {
             _popup = new PopupWindow();
-            _popup.Closed += (_, _) => _popup = null;
         }
-        PositionPopup();
         _popup.Show();
         _popup.Activate();
     }
 
-    private void PositionPopup()
-    {
-        if (_popup == null) return;
-        var workArea = SystemParameters.WorkArea;
-        _popup.Left = workArea.Right  - _popup.Width  - 8;
-        _popup.Top  = workArea.Bottom - _popup.Height - 8;
-    }
-
     public void ScheduleTimer(int seconds)
     {
         _timer?.Stop();

windows/Controls/GaugeControl.cs

@@ -21,6 +21,11 @@ public class GaugeControl : FrameworkElement
     public double Percent { get => (double)GetValue(PercentProperty); set => SetValue(PercentProperty, value); }
     public Brush  Accent  { get => (Brush)GetValue(AccentProperty);   set => SetValue(AccentProperty, value); }
 
+    public GaugeControl()
+    {
+        ThemeManager.ThemeChanged += InvalidateVisual;
+    }
+
     private const double StartAngleDeg = 135;
     private const double SweepDeg      = 270;
     private const double StrokeWidth   = 6;
@@ -31,8 +36,11 @@ public class GaugeControl : FrameworkElement
         var cy     = RenderSize.Height / 2;
         var radius = Math.Min(cx, cy) - StrokeWidth / 2 - 1;
 
+        var trackColor = ThemeManager.IsDark
+            ? Color.FromArgb(40, 255, 255, 255)
+            : Color.FromArgb(30, 0, 0, 0);
         DrawArc(dc, cx, cy, radius, StartAngleDeg, SweepDeg,
-            new Pen(new SolidColorBrush(Color.FromArgb(28, 255, 255, 255)), StrokeWidth));
+            new Pen(new SolidColorBrush(trackColor), StrokeWidth));
 
         if (Percent > 0)
             DrawArc(dc, cx, cy, radius, StartAngleDeg, SweepDeg * (Percent / 100.0),
@@ -40,18 +48,21 @@ public class GaugeControl : FrameworkElement
 
         var dpi = VisualTreeHelper.GetDpi(this).PixelsPerDip;
 
+        var textColor = ThemeManager.IsDark ? Color.FromRgb(0xF5, 0xF5, 0xF5) : Color.FromRgb(0x1C, 0x1C, 0x1C);
+        var subColor  = Color.FromRgb(0x9E, 0x9E, 0x9E);
+
         var pctText = new FormattedText(
             $"{(int)Math.Round(Percent)}%",
             CultureInfo.CurrentCulture, FlowDirection.LeftToRight,
             new Typeface(new FontFamily("Segoe UI"), FontStyles.Normal, FontWeights.Bold, FontStretches.Normal),
-            14, Brushes.White, dpi);
+            14, new SolidColorBrush(textColor), dpi);
         dc.DrawText(pctText, new Point(cx - pctText.Width / 2, cy - pctText.Height - 1));
 
         var sub = new FormattedText(
             "Updated\nnow",
             CultureInfo.CurrentCulture, FlowDirection.LeftToRight,
             new Typeface("Segoe UI"), 7,
-            new SolidColorBrush(Color.FromRgb(0x88, 0x88, 0x88)), dpi)
+            new SolidColorBrush(subColor), dpi)
         {
             TextAlignment = TextAlignment.Center
         };

windows/LoginWindow.xaml.cs

@@ -44,8 +44,8 @@ public partial class LoginWindow : Window
                     : "Complete sign-in, then click Done.";
             });
 
-            // Auto-close once clearly on the main app page
-            if (signedIn && (uri.Contains("/chats") || uri.Contains("/new") || uri == "https://claude.ai/"))
+            // Auto-close only on explicit post-login redirects, not on initial load
+            if (signedIn && (uri.Contains("/chats") || uri.Contains("/new")))
             {
                 await SaveAndClose(cookies);
             }

windows/PopupWindow.xaml

@@ -3,249 +3,246 @@
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:ctrl="clr-namespace:ClaudeCheckerWindows.Controls"
         Title="ClaudeChecker"
-        Width="480"
-        SizeToContent="Height"
-        WindowStyle="None"
-        AllowsTransparency="True"
-        Background="Transparent"
-        ShowInTaskbar="False"
-        Topmost="True"
+        Width="480" Height="660"
+        WindowStartupLocation="CenterScreen"
+        Background="{StaticResource BackgroundBrush}"
+        FontFamily="Segoe UI"
+        ShowInTaskbar="True"
         ResizeMode="NoResize">
 
-    <Border Background="{StaticResource BackgroundBrush}"
-            CornerRadius="12"
-            BorderBrush="{StaticResource BorderBrush}"
-            BorderThickness="0.5">
-        <Border.Effect>
-            <DropShadowEffect BlurRadius="24" ShadowDepth="4" Opacity="0.5" Color="Black"/>
-        </Border.Effect>
+    <Grid>
+        <!-- Main panel -->
+        <DockPanel x:Name="MainPanel">
 
-        <Grid>
-            <!-- Main panel -->
-            <StackPanel x:Name="MainPanel">
-
-                <!-- Header -->
-                <Grid Margin="16,11">
+            <!-- Update banner -->
+            <Border x:Name="UpdateBanner" DockPanel.Dock="Top" Visibility="Collapsed"
+                    Background="{StaticResource BannerBgBrush}"
+                    BorderBrush="{StaticResource BannerBorderBrush}" BorderThickness="0,0,0,1"
+                    Cursor="Hand" MouseLeftButtonUp="UpdateBanner_Click">
+                <Grid Margin="16,10">
                     <Grid.ColumnDefinitions>
                         <ColumnDefinition Width="Auto"/>
                         <ColumnDefinition Width="*"/>
                         <ColumnDefinition Width="Auto"/>
-                        <ColumnDefinition Width="6"/>
-                        <ColumnDefinition Width="Auto"/>
                     </Grid.ColumnDefinitions>
-
-                    <Image Grid.Column="0" Width="24" Height="24"
-                           Source="Assets/icon.png" RenderOptions.BitmapScalingMode="HighQuality"/>
-
-                    <TextBlock Grid.Column="1" Text="ClaudeChecker"
-                               FontSize="14" FontWeight="SemiBold" Foreground="White"
-                               VerticalAlignment="Center" Margin="10,0,0,0"/>
-
-                    <Button Grid.Column="2" Style="{StaticResource IconButton}"
-                            Click="Settings_Click" x:Name="SettingsButton">
-                        <TextBlock Text="⚙" FontSize="11" Foreground="{StaticResource SecondaryBrush}"/>
-                    </Button>
-                    <Button Grid.Column="4" Style="{StaticResource IconButton}"
-                            Click="Close_Click">
-                        <TextBlock Text="✕" FontSize="11" Foreground="{StaticResource SecondaryBrush}"/>
-                    </Button>
+                    <TextBlock Grid.Column="0" Text="⬇" FontSize="14"
+                               Foreground="{StaticResource BlueBrush}" VerticalAlignment="Center"/>
+                    <StackPanel Grid.Column="1" Margin="10,0">
+                        <TextBlock x:Name="UpdateBannerTitle" FontSize="12" FontWeight="SemiBold"
+                                   Foreground="{StaticResource TextBrush}"/>
+                        <TextBlock Text="Click to view release notes and install."
+                                   FontSize="11" Foreground="{StaticResource SecondaryBrush}"/>
+                    </StackPanel>
+                    <Button Grid.Column="2" Content="Update" Style="{StaticResource SmallButton}"
+                            Foreground="{StaticResource BlueBrush}" Click="UpdateBanner_Click"/>
                 </Grid>
+            </Border>
 
-                <Rectangle Height="0.5" Fill="{StaticResource BorderBrush}" Opacity="0.4"/>
-
-                <!-- Update banner -->
-                <Border x:Name="UpdateBanner" Visibility="Collapsed"
-                        Background="#0A3B82F6" Cursor="Hand" MouseLeftButtonUp="UpdateBanner_Click">
-                    <Grid Margin="16,10">
-                        <Grid.ColumnDefinitions>
-                            <ColumnDefinition Width="Auto"/>
-                            <ColumnDefinition Width="*"/>
-                            <ColumnDefinition Width="Auto"/>
-                        </Grid.ColumnDefinitions>
-                        <TextBlock Grid.Column="0" Text="⬇" FontSize="14"
-                                   Foreground="{StaticResource BlueBrush}" VerticalAlignment="Center"/>
-                        <StackPanel Grid.Column="1" Margin="10,0">
-                            <TextBlock x:Name="UpdateBannerTitle" FontSize="12" FontWeight="SemiBold" Foreground="White"/>
-                            <TextBlock Text="Tap to view what's new &amp; install."
-                                       FontSize="11" Foreground="{StaticResource SecondaryBrush}"/>
-                        </StackPanel>
-                        <Button Grid.Column="2" Content="Update"
-                                Style="{StaticResource SmallButton}"
-                                Background="{StaticResource BlueBrush}"
-                                Foreground="White" Click="UpdateBanner_Click"/>
-                    </Grid>
-                    <Border.Effect>
-                        <DropShadowEffect ShadowDepth="0" BlurRadius="0" Opacity="0"/>
-                    </Border.Effect>
-                </Border>
-                <Rectangle x:Name="UpdateBannerDiv" Height="0.5" Fill="{StaticResource BorderBrush}"
-                           Opacity="0.3" Visibility="Collapsed"/>
-
-                <!-- Limit cards -->
-                <ScrollViewer VerticalScrollBarVisibility="Hidden" MaxHeight="600">
-                    <StackPanel x:Name="CardsPanel" Margin="0,0,0,4"/>
-                </ScrollViewer>
-
-                <Rectangle Height="0.5" Fill="{StaticResource BorderBrush}" Opacity="0.3"/>
-
-                <!-- Footer -->
-                <Grid Margin="16,9">
+            <!-- Footer -->
+            <Border DockPanel.Dock="Bottom" BorderBrush="{StaticResource BorderBrush}"
+                    BorderThickness="0,1,0,0" Background="{StaticResource SurfaceBrush}">
+                <Grid Margin="12,8">
                     <Grid.ColumnDefinitions>
                         <ColumnDefinition Width="*"/>
                         <ColumnDefinition Width="Auto"/>
                         <ColumnDefinition Width="8"/>
                         <ColumnDefinition Width="Auto"/>
+                        <ColumnDefinition Width="8"/>
+                        <ColumnDefinition Width="Auto"/>
                     </Grid.ColumnDefinitions>
-                    <TextBlock x:Name="LastUpdatedText" Grid.Column="0"
-                               FontSize="10" Foreground="#60888888" VerticalAlignment="Center"/>
-                    <ProgressBar x:Name="LoadingBar" Grid.Column="1"
-                                 IsIndeterminate="True" Width="14" Height="14"
-                                 Visibility="Collapsed" Style="{x:Null}"/>
-                    <Button Grid.Column="3" Content="↻  Refresh"
+                    <StackPanel Grid.Column="0" Orientation="Horizontal" VerticalAlignment="Center">
+                        <ProgressBar x:Name="LoadingBar" IsIndeterminate="True"
+                                     Width="12" Height="12" Visibility="Collapsed"
+                                     Style="{x:Null}" Margin="0,0,6,0"/>
+                        <TextBlock x:Name="LastUpdatedText" FontSize="11"
+                                   Foreground="{StaticResource SecondaryBrush}" VerticalAlignment="Center"/>
+                    </StackPanel>
+                    <Button Grid.Column="1" Content="↻  Refresh"
                             Style="{StaticResource SmallButton}" Click="Refresh_Click"/>
+                    <Button Grid.Column="3" x:Name="SettingsButton" Content="⚙  Settings"
+                            Style="{StaticResource SmallButton}" Click="Settings_Click"/>
                 </Grid>
-            </StackPanel>
+            </Border>
 
-            <!-- Settings panel -->
-            <Border x:Name="SettingsPanel" Visibility="Collapsed"
-                    Background="{StaticResource BackgroundBrush}" CornerRadius="12">
-                <ScrollViewer VerticalScrollBarVisibility="Auto" MaxHeight="700">
-                    <StackPanel Margin="16">
+            <!-- Cards scroll area -->
+            <ScrollViewer VerticalScrollBarVisibility="Auto">
+                <StackPanel x:Name="CardsPanel" Margin="0,4,0,4"/>
+            </ScrollViewer>
+        </DockPanel>
 
+        <!-- Settings panel -->
+        <Border x:Name="SettingsPanel" Visibility="Collapsed"
+                Background="{StaticResource BackgroundBrush}">
+            <DockPanel>
+                <Border DockPanel.Dock="Top" BorderBrush="{StaticResource BorderBrush}"
+                        BorderThickness="0,0,0,1" Background="{StaticResource SurfaceBrush}" Padding="12,10">
+                    <Grid>
                         <Button Content="← Back" HorizontalAlignment="Left"
-                                Style="{StaticResource SmallButton}"
-                                BorderThickness="0" Foreground="{StaticResource BlueBrush}"
-                                Click="BackFromSettings_Click" Margin="0,0,0,12"/>
+                                Style="{StaticResource SmallButton}" BorderThickness="0"
+                                Foreground="{StaticResource BlueBrush}" Background="Transparent"
+                                Click="BackFromSettings_Click"/>
+                        <TextBlock Text="Settings" FontSize="14" FontWeight="SemiBold"
+                                   Foreground="{StaticResource TextBrush}"
+                                   HorizontalAlignment="Center" VerticalAlignment="Center"/>
+                    </Grid>
+                </Border>
 
-                        <TextBlock Text="Settings" FontSize="16" FontWeight="SemiBold"
-                                   Foreground="White" Margin="0,0,0,16"/>
+                <ScrollViewer VerticalScrollBarVisibility="Auto">
+                    <StackPanel Margin="20,16,20,20">
 
-                        <!-- Auth -->
-                        <TextBlock Text="🔐  Authentication" Style="{StaticResource HeaderText}" Margin="0,0,0,8"/>
-                        <StackPanel x:Name="AuthPanel" Margin="0,0,0,8"/>
-                        <TextBlock Text="Your session is stored locally and persists across restarts."
-                                   FontSize="11" Foreground="{StaticResource SecondaryBrush}"
-                                   TextWrapping="Wrap" Margin="0,0,0,8"/>
-                        <StackPanel Orientation="Horizontal" Margin="0,0,0,16">
-                            <Button x:Name="SignInButton" Content="Sign In"
-                                    Style="{StaticResource SmallButton}" Click="SignIn_Click" Margin="0,0,8,0"/>
-                            <Button x:Name="SignOutButton" Content="Sign Out"
-                                    Style="{StaticResource SmallButton}" Click="SignOut_Click"
-                                    Foreground="#EF4444" Visibility="Collapsed"/>
-                        </StackPanel>
-
-                        <Rectangle Height="0.5" Fill="{StaticResource BorderBrush}" Margin="0,0,0,16"/>
-
-                        <!-- Beta channel -->
-                        <TextBlock Text="📡  Update channel" Style="{StaticResource HeaderText}" Margin="0,0,0,8"/>
-                        <Grid Margin="0,0,0,16">
-                            <Grid.ColumnDefinitions>
-                                <ColumnDefinition Width="*"/>
-                                <ColumnDefinition Width="Auto"/>
-                            </Grid.ColumnDefinitions>
+                        <TextBlock Text="AUTHENTICATION" Style="{StaticResource HeaderText}" Margin="0,0,0,8"/>
+                        <Border Background="{StaticResource CardBrush}" CornerRadius="6"
+                                BorderBrush="{StaticResource BorderBrush}" BorderThickness="1"
+                                Padding="14,12" Margin="0,0,0,16">
                             <StackPanel>
-                                <TextBlock Text="Beta updates" FontSize="12" Foreground="White"/>
-                                <TextBlock Text="Receive early access builds — may be less stable"
-                                           FontSize="11" Foreground="{StaticResource SecondaryBrush}"/>
+                                <StackPanel x:Name="AuthPanel" Margin="0,0,0,10"/>
+                                <TextBlock Text="Your session is stored locally and persists across restarts."
+                                           FontSize="11" Foreground="{StaticResource SecondaryBrush}"
+                                           TextWrapping="Wrap" Margin="0,0,0,10"/>
+                                <StackPanel Orientation="Horizontal">
+                                    <Button x:Name="SignInButton" Content="Sign In"
+                                            Style="{StaticResource SmallButton}"
+                                            Click="SignIn_Click" Margin="0,0,8,0"/>
+                                    <Button x:Name="SignOutButton" Content="Sign Out"
+                                            Style="{StaticResource SmallButton}"
+                                            Click="SignOut_Click" Foreground="#C42B1C"
+                                            Visibility="Collapsed"/>
+                                </StackPanel>
                             </StackPanel>
-                            <CheckBox Grid.Column="1" x:Name="BetaToggle" VerticalAlignment="Center"
-                                      Checked="BetaToggle_Changed" Unchecked="BetaToggle_Changed"/>
-                        </Grid>
+                        </Border>
 
-                        <Rectangle Height="0.5" Fill="{StaticResource BorderBrush}" Margin="0,0,0,16"/>
+                        <TextBlock Text="UPDATE CHANNEL" Style="{StaticResource HeaderText}" Margin="0,0,0,8"/>
+                        <Border Background="{StaticResource CardBrush}" CornerRadius="6"
+                                BorderBrush="{StaticResource BorderBrush}" BorderThickness="1"
+                                Padding="14,12" Margin="0,0,0,16">
+                            <Grid>
+                                <Grid.ColumnDefinitions>
+                                    <ColumnDefinition Width="*"/>
+                                    <ColumnDefinition Width="Auto"/>
+                                </Grid.ColumnDefinitions>
+                                <StackPanel>
+                                    <TextBlock Text="Beta updates" FontSize="12" FontWeight="SemiBold"
+                                               Foreground="{StaticResource TextBrush}"/>
+                                    <TextBlock Text="Receive early access builds — may be less stable"
+                                               FontSize="11" Foreground="{StaticResource SecondaryBrush}"/>
+                                </StackPanel>
+                                <CheckBox Grid.Column="1" x:Name="BetaToggle" VerticalAlignment="Center"
+                                          Checked="BetaToggle_Changed" Unchecked="BetaToggle_Changed"/>
+                            </Grid>
+                        </Border>
 
-                        <!-- Refresh interval -->
-                        <TextBlock Text="⏱  Auto-refresh interval" Style="{StaticResource HeaderText}" Margin="0,0,0,8"/>
-                        <ComboBox x:Name="RefreshPicker" SelectionChanged="RefreshPicker_Changed"
-                                  Margin="0,0,0,16" FontSize="12"/>
+                        <TextBlock Text="AUTO-REFRESH" Style="{StaticResource HeaderText}" Margin="0,0,0,8"/>
+                        <Border Background="{StaticResource CardBrush}" CornerRadius="6"
+                                BorderBrush="{StaticResource BorderBrush}" BorderThickness="1"
+                                Padding="14,12" Margin="0,0,0,16">
+                            <Grid>
+                                <Grid.ColumnDefinitions>
+                                    <ColumnDefinition Width="*"/>
+                                    <ColumnDefinition Width="Auto"/>
+                                </Grid.ColumnDefinitions>
+                                <TextBlock Text="Refresh interval" FontSize="12" FontWeight="SemiBold"
+                                           Foreground="{StaticResource TextBrush}" VerticalAlignment="Center"/>
+                                <ComboBox Grid.Column="1" x:Name="RefreshPicker" Width="100"
+                                          SelectionChanged="RefreshPicker_Changed"/>
+                            </Grid>
+                        </Border>
 
-                        <Rectangle Height="0.5" Fill="{StaticResource BorderBrush}" Margin="0,0,0,16"/>
+                        <TextBlock Text="ABOUT" Style="{StaticResource HeaderText}" Margin="0,0,0,8"/>
+                        <Border Background="{StaticResource CardBrush}" CornerRadius="6"
+                                BorderBrush="{StaticResource BorderBrush}" BorderThickness="1"
+                                Padding="14,12">
+                            <Grid>
+                                <Grid.ColumnDefinitions>
+                                    <ColumnDefinition Width="Auto"/>
+                                    <ColumnDefinition Width="*"/>
+                                    <ColumnDefinition Width="Auto"/>
+                                </Grid.ColumnDefinitions>
+                                <Image Width="36" Height="36" Source="Assets/icon.png"
+                                       RenderOptions.BitmapScalingMode="HighQuality" Margin="0,0,12,0"/>
+                                <StackPanel Grid.Column="1" VerticalAlignment="Center">
+                                    <StackPanel Orientation="Horizontal">
+                                        <TextBlock Text="ClaudeChecker" FontSize="12" FontWeight="SemiBold"
+                                                   Foreground="{StaticResource TextBrush}"/>
+                                        <Border Background="#F0F0F0" CornerRadius="3"
+                                                Margin="6,0,0,0" Padding="5,1">
+                                            <TextBlock x:Name="VersionLabel" FontSize="11"
+                                                       Foreground="{StaticResource SecondaryBrush}"
+                                                       FontFamily="Consolas"/>
+                                        </Border>
+                                    </StackPanel>
+                                    <TextBlock Text="Built by superdooper86 &amp; claude"
+                                               FontSize="11" Foreground="{StaticResource SecondaryBrush}"/>
+                                </StackPanel>
+                                <Button Grid.Column="2" x:Name="CheckUpdateButton"
+                                        Style="{StaticResource SmallButton}"
+                                        Click="CheckUpdate_Click" VerticalAlignment="Center"/>
+                            </Grid>
+                        </Border>
 
-                        <!-- About -->
+                    </StackPanel>
+                </ScrollViewer>
+            </DockPanel>
+        </Border>
+
+        <!-- Update panel -->
+        <Border x:Name="UpdatePanel" Visibility="Collapsed"
+                Background="{StaticResource BackgroundBrush}">
+            <DockPanel>
+                <Border DockPanel.Dock="Top" BorderBrush="{StaticResource BorderBrush}"
+                        BorderThickness="0,0,0,1" Background="{StaticResource SurfaceBrush}" Padding="12,10">
+                    <Grid>
+                        <Button Content="← Back" HorizontalAlignment="Left"
+                                Style="{StaticResource SmallButton}" BorderThickness="0"
+                                Foreground="{StaticResource BlueBrush}" Background="Transparent"
+                                Click="CloseUpdate_Click"/>
+                        <TextBlock Text="Update Available" FontSize="14" FontWeight="SemiBold"
+                                   Foreground="{StaticResource TextBrush}"
+                                   HorizontalAlignment="Center" VerticalAlignment="Center"/>
+                        <Button x:Name="NotNowButton" Content="Not Now" HorizontalAlignment="Right"
+                                Style="{StaticResource SmallButton}" Click="CloseUpdate_Click"/>
+                    </Grid>
+                </Border>
+
+                <StackPanel Margin="20,16">
+                    <Border Background="{StaticResource CardBrush}" CornerRadius="6"
+                            BorderBrush="{StaticResource BorderBrush}" BorderThickness="1"
+                            Padding="14,12" Margin="0,0,0,12">
                         <Grid>
                             <Grid.ColumnDefinitions>
                                 <ColumnDefinition Width="Auto"/>
                                 <ColumnDefinition Width="*"/>
-                                <ColumnDefinition Width="Auto"/>
                             </Grid.ColumnDefinitions>
-                            <Image Width="36" Height="36" Source="Assets/icon.png"
-                                   RenderOptions.BitmapScalingMode="HighQuality" Margin="0,0,12,0"/>
-                            <StackPanel Grid.Column="1" VerticalAlignment="Center">
-                                <StackPanel Orientation="Horizontal">
-                                    <TextBlock Text="ClaudeChecker" FontSize="12" FontWeight="SemiBold" Foreground="White"/>
-                                    <Border Background="#0FFFFFFF" CornerRadius="4" Margin="6,0,0,0" Padding="5,1">
-                                        <TextBlock x:Name="VersionLabel" FontSize="11"
-                                                   Foreground="{StaticResource SecondaryBrush}"
-                                                   FontFamily="Consolas"/>
-                                    </Border>
-                                </StackPanel>
-                                <TextBlock Text="Built by superdooper86 &amp; claude"
-                                           FontSize="11" Foreground="{StaticResource SecondaryBrush}"/>
-                            </StackPanel>
-                            <Button Grid.Column="2" x:Name="CheckUpdateButton"
-                                    Style="{StaticResource SmallButton}" Click="CheckUpdate_Click"
-                                    VerticalAlignment="Center"/>
-                        </Grid>
-
-                    </StackPanel>
-                </ScrollViewer>
-            </Border>
-
-            <!-- Update sheet -->
-            <Border x:Name="UpdatePanel" Visibility="Collapsed"
-                    Background="{StaticResource BackgroundBrush}" CornerRadius="12">
-                <StackPanel>
-                    <Grid Margin="16,12">
-                        <Grid.ColumnDefinitions>
-                            <ColumnDefinition Width="*"/>
-                            <ColumnDefinition Width="Auto"/>
-                        </Grid.ColumnDefinitions>
-                        <TextBlock Text="Update ClaudeChecker" FontSize="14" FontWeight="SemiBold"
-                                   Foreground="White" VerticalAlignment="Center"/>
-                        <Button Grid.Column="1" Content="Not Now" Style="{StaticResource SmallButton}"
-                                Click="CloseUpdate_Click" x:Name="NotNowButton"/>
-                    </Grid>
-                    <Rectangle Height="0.5" Fill="{StaticResource BorderBrush}"/>
-                    <StackPanel Margin="20">
-                        <Grid Margin="0,0,0,16">
-                            <Grid.ColumnDefinitions>
-                                <ColumnDefinition Width="Auto"/>
-                                <ColumnDefinition Width="*"/>
-                            </Grid.ColumnDefinitions>
-                            <Image Width="48" Height="48" Source="Assets/icon.png"
+                            <Image Width="44" Height="44" Source="Assets/icon.png"
                                    RenderOptions.BitmapScalingMode="HighQuality" Margin="0,0,14,0"/>
                             <StackPanel Grid.Column="1" VerticalAlignment="Center">
-                                <StackPanel Orientation="Horizontal">
+                                <StackPanel Orientation="Horizontal" Margin="0,0,0,4">
                                     <TextBlock x:Name="CurrentVerLabel" FontSize="12" FontFamily="Consolas"
-                                               Foreground="{StaticResource SecondaryBrush}"/>
-                                    <TextBlock Text=" → " FontSize="10"
                                                Foreground="{StaticResource SecondaryBrush}" VerticalAlignment="Center"/>
+                                    <TextBlock Text=" → " FontSize="11" Foreground="{StaticResource SecondaryBrush}"
+                                               VerticalAlignment="Center"/>
                                     <TextBlock x:Name="NewVerLabel" FontSize="13" FontWeight="SemiBold"
-                                               FontFamily="Consolas" Foreground="{StaticResource BlueBrush}"/>
+                                               FontFamily="Consolas" Foreground="{StaticResource BlueBrush}"
+                                               VerticalAlignment="Center"/>
                                 </StackPanel>
                                 <TextBlock x:Name="ReleaseNotesText" FontSize="11" TextWrapping="Wrap"
-                                           Foreground="{StaticResource SecondaryBrush}" Margin="0,4,0,0"
-                                           MaxHeight="180"/>
+                                           Foreground="{StaticResource SecondaryBrush}" MaxHeight="160"/>
                             </StackPanel>
                         </Grid>
+                    </Border>
 
-                        <TextBlock x:Name="UpdateStatusText" Foreground="{StaticResource SecondaryBrush}"
-                                   FontSize="11" TextWrapping="Wrap" TextAlignment="Center"
-                                   Visibility="Collapsed" Margin="0,0,0,10"/>
-
-                        <ProgressBar x:Name="UpdateProgress" Visibility="Collapsed"
-                                     Height="4" Margin="0,0,0,12" Foreground="{StaticResource BlueBrush}"/>
-
-                        <TextBlock Text="ClaudeChecker will download the update, replace itself, and relaunch automatically."
-                                   FontSize="11" Foreground="{StaticResource SecondaryBrush}"
-                                   TextWrapping="Wrap" TextAlignment="Center" Margin="0,0,0,12"/>
-
-                        <Button x:Name="InstallButton" Content="⬇  Install Update"
-                                Style="{StaticResource PrimaryButton}" HorizontalAlignment="Stretch"
-                                Click="Install_Click"/>
-                    </StackPanel>
+                    <TextBlock x:Name="UpdateStatusText" Foreground="{StaticResource SecondaryBrush}"
+                               FontSize="11" TextWrapping="Wrap" TextAlignment="Center"
+                               Visibility="Collapsed" Margin="0,0,0,8"/>
+                    <ProgressBar x:Name="UpdateProgress" Visibility="Collapsed"
+                                 Height="4" Margin="0,0,0,12" Foreground="{StaticResource BlueBrush}"/>
+                    <TextBlock Text="ClaudeChecker will download, replace itself, and relaunch automatically."
+                               FontSize="11" Foreground="{StaticResource SecondaryBrush}"
+                               TextWrapping="Wrap" TextAlignment="Center" Margin="0,0,0,12"/>
+                    <Button x:Name="InstallButton" Content="⬇  Download &amp; Install"
+                            Style="{StaticResource PrimaryButton}" HorizontalAlignment="Stretch"
+                            Click="Install_Click"/>
                 </StackPanel>
-            </Border>
-        </Grid>
-    </Border>
+            </DockPanel>
+        </Border>
+    </Grid>
 </Window>

windows/PopupWindow.xaml.cs

@@ -1,7 +1,9 @@
 using ClaudeCheckerWindows.Controls;
 using System;
+using System.Runtime.InteropServices;
 using System.Windows;
 using System.Windows.Controls;
+using System.Windows.Interop;
 using System.Windows.Media;
 using System.Windows.Threading;
 
@@ -12,6 +14,18 @@ public partial class PopupWindow : Window
     private static readonly UsageViewModel VM      = App.ViewModel;
     private static readonly UpdateManager  Updater = App.Updater;
     private readonly DispatcherTimer _clockTimer;
+    private bool _dialogOpen;
+
+    [DllImport("dwmapi.dll")]
+    private static extern int DwmSetWindowAttribute(IntPtr hwnd, int attr, ref int value, int size);
+
+    private void ApplyTitleBarTheme()
+    {
+        var hwnd = new WindowInteropHelper(this).Handle;
+        if (hwnd == IntPtr.Zero) return;
+        int dark = ThemeManager.IsDark ? 1 : 0;
+        DwmSetWindowAttribute(hwnd, 20, ref dark, sizeof(int));
+    }
 
     public PopupWindow()
     {
@@ -29,7 +43,9 @@ public partial class PopupWindow : Window
         UpdateBannerState();
         UpdateFooter();
 
-        Deactivated += (_, _) => Hide();
+        Closing += (_, e) => { e.Cancel = true; Hide(); };
+        SourceInitialized += (_, _) => ApplyTitleBarTheme();
+        ThemeManager.ThemeChanged += () => { ApplyTitleBarTheme(); RebuildCards(); };
     }
 
     // ── Card rendering ───────────────────────────────────────────────
@@ -43,8 +59,10 @@ public partial class PopupWindow : Window
 
     private static UIElement BuildCard(AgentLimit limit)
     {
-        var accent     = new SolidColorBrush(Color.FromRgb(0xF9, 0x73, 0x16));
-        var secondary  = (SolidColorBrush)Application.Current.Resources["SecondaryBrush"];
+        var accent    = new SolidColorBrush(Color.FromRgb(0xF9, 0x73, 0x16));
+        var text      = (SolidColorBrush)Application.Current.Resources["TextBrush"];
+        var secondary = (SolidColorBrush)Application.Current.Resources["SecondaryBrush"];
+        var border    = (SolidColorBrush)Application.Current.Resources["BorderBrush"];
 
         // Gauge
         var gauge = new GaugeControl { Width = 76, Height = 76, Percent = limit.UsedPercent, Accent = accent };
@@ -52,26 +70,25 @@ public partial class PopupWindow : Window
         // Live badge
         var liveBadge = new Border
         {
-            Background   = new SolidColorBrush(Color.FromArgb(26, 0, 200, 0)),
+            Background   = new SolidColorBrush(Color.FromArgb(30, 0, 160, 0)),
             CornerRadius = new CornerRadius(4),
             Padding      = new Thickness(6, 2, 6, 2),
             Margin       = new Thickness(0, 0, 6, 0),
             Visibility   = limit.IsLive ? Visibility.Visible : Visibility.Collapsed,
             Child        = new TextBlock { Text = "Live", FontSize = 10, FontWeight = FontWeights.Medium,
-                               Foreground = new SolidColorBrush(Colors.LightGreen) }
+                               Foreground = new SolidColorBrush(Color.FromRgb(0, 120, 0)) }
         };
 
         // Usage badge
         var usageBadge = new Border
         {
-            Background   = new SolidColorBrush(Color.FromArgb(15, 255, 255, 255)),
+            Background   = new SolidColorBrush(Color.FromArgb(18, 0, 0, 0)),
             CornerRadius = new CornerRadius(4),
             Padding      = new Thickness(6, 2, 6, 2),
             Child        = new TextBlock { Text = $"Usg: {limit.UsageLabel}", FontSize = 10,
                                FontWeight = FontWeights.Medium, Foreground = secondary }
         };
 
-        // Header row: Claude · Pro | [Live] [Usg]
         var badgeStack = new StackPanel { Orientation = Orientation.Horizontal };
         badgeStack.Children.Add(liveBadge);
         badgeStack.Children.Add(usageBadge);
@@ -79,7 +96,7 @@ public partial class PopupWindow : Window
         var nameStack = new StackPanel { Orientation = Orientation.Horizontal, VerticalAlignment = VerticalAlignment.Center };
         nameStack.Children.Add(new TextBlock { Text = "✦", FontSize = 11, Foreground = accent, VerticalAlignment = VerticalAlignment.Center });
         nameStack.Children.Add(new TextBlock { Text = "Claude", FontSize = 13, FontWeight = FontWeights.SemiBold,
-            Foreground = Brushes.White, Margin = new Thickness(6, 0, 0, 0), VerticalAlignment = VerticalAlignment.Center });
+            Foreground = text, Margin = new Thickness(6, 0, 0, 0), VerticalAlignment = VerticalAlignment.Center });
         nameStack.Children.Add(new TextBlock { Text = $"·  {VM.PlanLabel}", FontSize = 11,
             Foreground = secondary, Margin = new Thickness(6, 0, 0, 0), VerticalAlignment = VerticalAlignment.Center });
 
@@ -91,21 +108,19 @@ public partial class PopupWindow : Window
         headerRow.Children.Add(nameStack);
         headerRow.Children.Add(badgeStack);
 
-        // Progress bar
         var progress = new ProgressBar
         {
             Value = limit.UsedPercent, Maximum = 100, Height = 4,
             Margin = new Thickness(0, 4, 0, 4),
             Foreground = accent,
-            Background = new SolidColorBrush(Color.FromArgb(18, 255, 255, 255)),
+            Background = new SolidColorBrush(Color.FromArgb(20, 0, 0, 0)),
             BorderThickness = new Thickness(0),
         };
 
-        // Time row
         var timeStack = new StackPanel { Orientation = Orientation.Horizontal, VerticalAlignment = VerticalAlignment.Center };
         timeStack.Children.Add(new TextBlock { Text = "⏱ ", FontSize = 10, Foreground = secondary, VerticalAlignment = VerticalAlignment.Center });
         timeStack.Children.Add(new TextBlock { Text = limit.TimeRemaining, FontSize = 12,
-            FontWeight = FontWeights.Medium, Foreground = Brushes.White, VerticalAlignment = VerticalAlignment.Center });
+            FontWeight = FontWeights.Medium, Foreground = text, VerticalAlignment = VerticalAlignment.Center });
 
         var resetText = new TextBlock
         {
@@ -116,26 +131,23 @@ public partial class PopupWindow : Window
         var timeRow = new Grid();
         timeRow.ColumnDefinitions.Add(new ColumnDefinition { Width = new GridLength(1, GridUnitType.Star) });
         timeRow.ColumnDefinitions.Add(new ColumnDefinition { Width = GridLength.Auto });
-        Grid.SetColumn(timeStack,  0);
-        Grid.SetColumn(resetText,  1);
+        Grid.SetColumn(timeStack, 0);
+        Grid.SetColumn(resetText, 1);
         timeRow.Children.Add(timeStack);
         timeRow.Children.Add(resetText);
 
-        // Sparkline
         var sparkline = new SparklineControl
         {
             Height = 28, Margin = new Thickness(0, 8, 0, 0), LineColor = Color.FromRgb(0xF9, 0x73, 0x16),
             Data = limit.BurnHistory.Count > 0 ? limit.BurnHistory : null,
         };
 
-        // Info panel
         var infoPanel = new StackPanel { VerticalAlignment = VerticalAlignment.Center };
         infoPanel.Children.Add(headerRow);
         infoPanel.Children.Add(progress);
         infoPanel.Children.Add(timeRow);
         infoPanel.Children.Add(sparkline);
 
-        // Card content grid
         var cardGrid = new Grid { Margin = new Thickness(16, 12, 16, 12) };
         cardGrid.ColumnDefinitions.Add(new ColumnDefinition { Width = GridLength.Auto });
         cardGrid.ColumnDefinitions.Add(new ColumnDefinition { Width = new GridLength(16, GridUnitType.Pixel) });
@@ -148,10 +160,10 @@ public partial class PopupWindow : Window
         var card = new Border
         {
             Background      = (SolidColorBrush)Application.Current.Resources["CardBrush"],
-            CornerRadius    = new CornerRadius(8),
-            BorderBrush     = new SolidColorBrush(Color.FromArgb(20, 255, 255, 255)),
-            BorderThickness = new Thickness(0.5),
-            Margin          = new Thickness(8, 0, 8, 0),
+            CornerRadius    = new CornerRadius(6),
+            BorderBrush     = border,
+            BorderThickness = new Thickness(1),
+            Margin          = new Thickness(12, 0, 12, 0),
             Child           = cardGrid,
         };
 
@@ -159,7 +171,7 @@ public partial class PopupWindow : Window
         {
             Text   = limit.WindowLabel,
             Style  = (Style)Application.Current.Resources["HeaderText"],
-            Margin = new Thickness(16, 10, 16, 4),
+            Margin = new Thickness(16, 12, 16, 6),
         };
 
         var section = new StackPanel();
@@ -178,6 +190,10 @@ public partial class PopupWindow : Window
             RebuildCards();
             UpdateFooter();
         }
+        if (prop is nameof(UsageViewModel.IsSignedIn) or nameof(UsageViewModel.UserEmail))
+        {
+            InitSettings();
+        }
     }
 
     private void OnUpdaterChanged(string? prop)
@@ -195,8 +211,7 @@ public partial class PopupWindow : Window
     private void UpdateBannerState()
     {
         var visible = Updater.UpdateAvailable;
-        UpdateBanner.Visibility    = visible ? Visibility.Visible : Visibility.Collapsed;
-        UpdateBannerDiv.Visibility = visible ? Visibility.Visible : Visibility.Collapsed;
+        UpdateBanner.Visibility = visible ? Visibility.Visible : Visibility.Collapsed;
         if (visible) UpdateBannerTitle.Text = $"Update available — v{Updater.LatestVersion}";
     }
 
@@ -271,8 +286,6 @@ public partial class PopupWindow : Window
         UpdatePanel.Visibility   = Visibility.Collapsed;
     }
 
-    private void Close_Click(object s, RoutedEventArgs e) => Hide();
-
     private async void Refresh_Click(object s, RoutedEventArgs e) => await VM.RefreshAsync();
 
     private void UpdateBanner_Click(object s, RoutedEventArgs e) => ShowUpdatePanel();
@@ -297,14 +310,18 @@ public partial class PopupWindow : Window
         await Updater.DownloadAndInstallAsync();
     }
 
-    private void SignIn_Click(object s, RoutedEventArgs e)
+    private async void SignIn_Click(object s, RoutedEventArgs e)
     {
+        _dialogOpen = true;
         var login = new LoginWindow { Owner = this };
         if (login.ShowDialog() == true)
         {
-            _ = VM.RefreshAsync();
+            await VM.RefreshAsync();
             InitSettings();
         }
+        _dialogOpen = false;
+        Show();
+        Activate();
     }
 
     private async void SignOut_Click(object s, RoutedEventArgs e)

windows/ThemeManager.cs

@@ -0,0 +1,79 @@
+using Microsoft.Win32;
+using System;
+using System.Windows;
+using System.Windows.Media;
+
+namespace ClaudeCheckerWindows;
+
+public static class ThemeManager
+{
+    public static bool IsDark { get; private set; }
+    public static event Action? ThemeChanged;
+
+    public static void Initialize()
+    {
+        IsDark = ReadIsDark();
+        Apply();
+        SystemEvents.UserPreferenceChanged += OnPreferenceChanged;
+    }
+
+    private static void OnPreferenceChanged(object sender, UserPreferenceChangedEventArgs e)
+    {
+        if (e.Category != UserPreferenceCategory.General) return;
+        var nowDark = ReadIsDark();
+        if (nowDark == IsDark) return;
+        IsDark = nowDark;
+        Application.Current.Dispatcher.Invoke(() =>
+        {
+            Apply();
+            ThemeChanged?.Invoke();
+        });
+    }
+
+    private static bool ReadIsDark()
+    {
+        try
+        {
+            using var key = Registry.CurrentUser.OpenSubKey(
+                @"Software\Microsoft\Windows\CurrentVersion\Themes\Personalize");
+            return (int)(key?.GetValue("AppsUseLightTheme") ?? 1) == 0;
+        }
+        catch { return false; }
+    }
+
+    private static void Apply()
+    {
+        var res = Application.Current.Resources;
+        if (IsDark)
+        {
+            Set(res, "BackgroundBrush",   Color.FromRgb(0x1C, 0x1C, 0x1E));
+            Set(res, "CardBrush",         Color.FromRgb(0x2C, 0x2C, 0x2E));
+            Set(res, "TextBrush",         Color.FromRgb(0xF5, 0xF5, 0xF5));
+            Set(res, "SecondaryBrush",    Color.FromRgb(0x8A, 0x8A, 0x8E));
+            Set(res, "BorderBrush",       Color.FromRgb(0x3A, 0x3A, 0x3C));
+            Set(res, "BlueBrush",         Color.FromRgb(0x3B, 0x82, 0xF6));
+            Set(res, "ButtonBrush",       Color.FromRgb(0x3A, 0x3A, 0x3C));
+            Set(res, "SurfaceBrush",      Color.FromRgb(0x25, 0x25, 0x27));
+            Set(res, "BannerBgBrush",     Color.FromRgb(0x1A, 0x31, 0x52));
+            Set(res, "BannerBorderBrush", Color.FromRgb(0x2A, 0x4A, 0x72));
+        }
+        else
+        {
+            Set(res, "BackgroundBrush",   Color.FromRgb(0xF3, 0xF3, 0xF3));
+            Set(res, "CardBrush",         Colors.White);
+            Set(res, "TextBrush",         Color.FromRgb(0x1C, 0x1C, 0x1C));
+            Set(res, "SecondaryBrush",    Color.FromRgb(0x6E, 0x6E, 0x6E));
+            Set(res, "BorderBrush",       Color.FromRgb(0xE0, 0xE0, 0xE0));
+            Set(res, "BlueBrush",         Color.FromRgb(0x00, 0x78, 0xD4));
+            Set(res, "ButtonBrush",       Colors.White);
+            Set(res, "SurfaceBrush",      Color.FromRgb(0xFA, 0xFA, 0xFA));
+            Set(res, "BannerBgBrush",     Color.FromRgb(0xE8, 0xF2, 0xFB));
+            Set(res, "BannerBorderBrush", Color.FromRgb(0xB3, 0xD6, 0xF5));
+        }
+    }
+
+    private static void Set(ResourceDictionary res, string key, Color color)
+    {
+        if (res[key] is SolidColorBrush b) b.Color = color;
+    }
+}