diff --git a/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml b/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml
index cf74a38..1850aad 100644
--- a/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml
+++ b/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml
@@ -1,6 +1,7 @@
 <Window xmlns="https://github.com/avaloniaui"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:vm="using:ClaudeDo.Ui.ViewModels.Modals"
+        xmlns:ctl="using:ClaudeDo.Ui.Views.Controls"
         x:Class="ClaudeDo.Ui.Views.Modals.DiffModalView"
         x:DataType="vm:DiffModalViewModel"
         Title="Diff"
@@ -8,7 +9,7 @@
         WindowDecorations="None"
         ExtendClientAreaToDecorationsHint="True"
         WindowStartupLocation="CenterOwner"
-        Background="{StaticResource SurfaceBrush}">
+        Background="{DynamicResource SurfaceBrush}">
 
   <Window.KeyBindings>
     <KeyBinding Gesture="Escape" Command="{Binding CloseCommand}"/>
@@ -17,10 +18,10 @@
   <Window.Styles>
     <!-- diff line row tints via Tag selector (compiled-binding-friendly) -->
     <Style Selector="Border.diff-line[Tag=add]">
-      <Setter Property="Background" Value="#1A4A6B4A"/>
+      <Setter Property="Background" Value="{StaticResource RunningTintBrush}"/>
     </Style>
     <Style Selector="Border.diff-line[Tag=del]">
-      <Setter Property="Background" Value="#1AC87060"/>
+      <Setter Property="Background" Value="{StaticResource ErrorTintBrush}"/>
     </Style>
     <Style Selector="Border.diff-line[Tag=ctx]">
       <Setter Property="Background" Value="Transparent"/>
@@ -45,136 +46,114 @@
     </Style>
   </Window.Styles>
 
-  <!-- Outer container — rectangular so the OS window rectangle stays filled (no black corners) -->
-  <Border Background="{StaticResource SurfaceBrush}"
-          BorderBrush="{StaticResource LineBrush}"
-          BorderThickness="1">
-    <Grid RowDefinitions="36,*">
+  <ctl:ModalShell Title="DIFF" CloseCommand="{Binding CloseCommand}">
+    <ctl:ModalShell.Footer>
+      <StackPanel Orientation="Horizontal" Spacing="8"
+                  HorizontalAlignment="Right" VerticalAlignment="Center"
+                  Margin="16,0">
+        <Button Content="Merge…" Command="{Binding MergeCommand}"/>
+      </StackPanel>
+    </ctl:ModalShell.Footer>
 
-      <!-- Title bar / drag handle -->
-      <Border Grid.Row="0"
-              x:Name="TitleBar"
-              Background="{StaticResource Surface2Brush}"
-              BorderBrush="{StaticResource LineBrush}"
-              BorderThickness="0,0,0,1"
-              PointerPressed="TitleBar_PointerPressed">
-        <Grid ColumnDefinitions="*,Auto" Margin="14,0">
-          <TextBlock Text="Diff" VerticalAlignment="Center"
-                     FontFamily="{StaticResource MonoFamily}"
-                     FontSize="12"
-                     Foreground="{StaticResource TextDimBrush}"/>
-          <StackPanel Grid.Column="1" Orientation="Horizontal" Spacing="4" VerticalAlignment="Center">
-            <Button Content="Merge…"
-                    Command="{Binding MergeCommand}"
-                    Margin="0,0,4,0" />
-            <Button Classes="icon-btn"
-                    Content="✕"
-                    FontSize="12"
-                    Command="{Binding CloseCommand}" />
-          </StackPanel>
-        </Grid>
+    <!-- Body: sidebar + diff content -->
+    <Grid ColumnDefinitions="240,*">
+
+      <!-- File sidebar -->
+      <Border Grid.Column="0"
+              BorderBrush="{DynamicResource LineBrush}"
+              BorderThickness="0,0,1,0"
+              Background="{DynamicResource DeepBrush}">
+        <ListBox ItemsSource="{Binding Files}"
+                 SelectedItem="{Binding SelectedFile, Mode=TwoWay}"
+                 Background="Transparent"
+                 BorderThickness="0"
+                 ScrollViewer.HorizontalScrollBarVisibility="Disabled">
+          <ListBox.ItemTemplate>
+            <DataTemplate x:DataType="vm:DiffFileViewModel">
+              <Border Padding="10,8" Background="Transparent">
+                <StackPanel Spacing="4">
+                  <TextBlock Text="{Binding Path}"
+                             FontFamily="{DynamicResource MonoFont}"
+                             FontSize="{StaticResource FontSizeMono}"
+                             Foreground="{DynamicResource TextDimBrush}"
+                             TextTrimming="PrefixCharacterEllipsis"/>
+                  <StackPanel Orientation="Horizontal" Spacing="6">
+                    <Border Classes="chip" Padding="5,2">
+                      <TextBlock Foreground="{DynamicResource MossBrightBrush}"
+                                 FontFamily="{DynamicResource MonoFont}"
+                                 FontSize="{StaticResource FontSizeEyebrow}"
+                                 Text="{Binding Additions, StringFormat='+{0}'}"/>
+                    </Border>
+                    <Border Classes="chip" Padding="5,2">
+                      <TextBlock Foreground="{DynamicResource BloodBrush}"
+                                 FontFamily="{DynamicResource MonoFont}"
+                                 FontSize="{StaticResource FontSizeEyebrow}"
+                                 Text="{Binding Deletions, StringFormat='−{0}'}"/>
+                    </Border>
+                  </StackPanel>
+                </StackPanel>
+              </Border>
+            </DataTemplate>
+          </ListBox.ItemTemplate>
+        </ListBox>
       </Border>
 
-      <!-- Body: sidebar + diff content -->
-      <Grid Grid.Row="1" ColumnDefinitions="240,*">
-
-        <!-- File sidebar -->
-        <Border Grid.Column="0"
-                BorderBrush="{StaticResource LineBrush}"
-                BorderThickness="0,0,1,0"
-                Background="{StaticResource DeepBrush}">
-          <ListBox ItemsSource="{Binding Files}"
-                   SelectedItem="{Binding SelectedFile, Mode=TwoWay}"
-                   Background="Transparent"
-                   BorderThickness="0"
-                   ScrollViewer.HorizontalScrollBarVisibility="Disabled">
-            <ListBox.ItemTemplate>
-              <DataTemplate x:DataType="vm:DiffFileViewModel">
-                <Border Padding="10,8" Background="Transparent">
-                  <StackPanel Spacing="4">
-                    <TextBlock Text="{Binding Path}"
-                               FontFamily="{StaticResource MonoFamily}"
-                               FontSize="11"
-                               Foreground="{StaticResource TextDimBrush}"
-                               TextTrimming="PrefixCharacterEllipsis"/>
-                    <StackPanel Orientation="Horizontal" Spacing="6">
-                      <Border Classes="chip" Padding="5,2">
-                        <TextBlock Foreground="{StaticResource MossBrightBrush}"
-                                   FontFamily="{StaticResource MonoFamily}"
-                                   FontSize="10"
-                                   Text="{Binding Additions, StringFormat='+{0}'}"/>
-                      </Border>
-                      <Border Classes="chip" Padding="5,2">
-                        <TextBlock Foreground="{StaticResource BloodBrush}"
-                                   FontFamily="{StaticResource MonoFamily}"
-                                   FontSize="10"
-                                   Text="{Binding Deletions, StringFormat='\u2212{0}'}"/>
-                      </Border>
-                    </StackPanel>
-                  </StackPanel>
-                </Border>
-              </DataTemplate>
-            </ListBox.ItemTemplate>
-          </ListBox>
-        </Border>
-
-        <!-- Diff content -->
-        <Grid Grid.Column="1" Background="{StaticResource VoidBrush}">
-          <TextBlock Text="{Binding StatusMessage}"
-                     IsVisible="{Binding StatusMessage, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"
-                     HorizontalAlignment="Center"
-                     VerticalAlignment="Center"
-                     Foreground="{StaticResource TextDimBrush}"
-                     FontFamily="{StaticResource MonoFamily}"
-                     FontSize="12"/>
-          <ScrollViewer HorizontalScrollBarVisibility="Auto"
-                      VerticalScrollBarVisibility="Auto">
-          <ItemsControl ItemsSource="{Binding SelectedFile.Lines}">
-            <ItemsControl.ItemTemplate>
-              <DataTemplate x:DataType="vm:DiffLineViewModel">
-                <Border Classes="diff-line"
-                        Tag="{Binding ClassName}"
-                        Padding="4,1">
-                  <Grid ColumnDefinitions="48,48,16,*">
-                    <!-- Old line number -->
-                    <TextBlock Grid.Column="0"
-                               Text="{Binding OldNo}"
-                               Classes="diff-lineno"
-                               FontFamily="{StaticResource MonoFamily}"
-                               FontSize="11"
-                               Foreground="{StaticResource TextFaintBrush}"
-                               HorizontalAlignment="Right"
-                               Margin="0,0,8,0"/>
-                    <!-- New line number -->
-                    <TextBlock Grid.Column="1"
-                               Text="{Binding NewNo}"
-                               Classes="diff-lineno"
-                               FontFamily="{StaticResource MonoFamily}"
-                               FontSize="11"
-                               Foreground="{StaticResource TextFaintBrush}"
-                               HorizontalAlignment="Right"
-                               Margin="0,0,8,0"/>
-                    <!-- Sign -->
-                    <TextBlock Grid.Column="2"
-                               Classes="diff-sign"
-                               Text="{Binding Sign}"
-                               FontFamily="{StaticResource MonoFamily}"
-                               FontSize="11"/>
-                    <!-- Line text -->
-                    <TextBlock Grid.Column="3"
-                               Classes="diff-text"
-                               Text="{Binding Text}"
-                               FontFamily="{StaticResource MonoFamily}"
-                               FontSize="11"
-                               TextWrapping="NoWrap"/>
-                  </Grid>
-                </Border>
-              </DataTemplate>
-            </ItemsControl.ItemTemplate>
-          </ItemsControl>
-          </ScrollViewer>
-        </Grid>
+      <!-- Diff content -->
+      <Grid Grid.Column="1" Background="{DynamicResource VoidBrush}">
+        <TextBlock Text="{Binding StatusMessage}"
+                   IsVisible="{Binding StatusMessage, Converter={x:Static StringConverters.IsNotNullOrEmpty}}"
+                   HorizontalAlignment="Center"
+                   VerticalAlignment="Center"
+                   Foreground="{DynamicResource TextDimBrush}"
+                   FontFamily="{DynamicResource MonoFont}"
+                   FontSize="{StaticResource FontSizeBody}"/>
+        <ScrollViewer HorizontalScrollBarVisibility="Auto"
+                    VerticalScrollBarVisibility="Auto">
+        <ItemsControl ItemsSource="{Binding SelectedFile.Lines}">
+          <ItemsControl.ItemTemplate>
+            <DataTemplate x:DataType="vm:DiffLineViewModel">
+              <Border Classes="diff-line"
+                      Tag="{Binding ClassName}"
+                      Padding="4,1">
+                <Grid ColumnDefinitions="48,48,16,*">
+                  <!-- Old line number -->
+                  <TextBlock Grid.Column="0"
+                             Text="{Binding OldNo}"
+                             Classes="diff-lineno"
+                             FontFamily="{DynamicResource MonoFont}"
+                             FontSize="{StaticResource FontSizeMono}"
+                             Foreground="{DynamicResource TextFaintBrush}"
+                             HorizontalAlignment="Right"
+                             Margin="0,0,8,0"/>
+                  <!-- New line number -->
+                  <TextBlock Grid.Column="1"
+                             Text="{Binding NewNo}"
+                             Classes="diff-lineno"
+                             FontFamily="{DynamicResource MonoFont}"
+                             FontSize="{StaticResource FontSizeMono}"
+                             Foreground="{DynamicResource TextFaintBrush}"
+                             HorizontalAlignment="Right"
+                             Margin="0,0,8,0"/>
+                  <!-- Sign -->
+                  <TextBlock Grid.Column="2"
+                             Classes="diff-sign"
+                             Text="{Binding Sign}"
+                             FontFamily="{DynamicResource MonoFont}"
+                             FontSize="{StaticResource FontSizeMono}"/>
+                  <!-- Line text -->
+                  <TextBlock Grid.Column="3"
+                             Classes="diff-text"
+                             Text="{Binding Text}"
+                             FontFamily="{DynamicResource MonoFont}"
+                             FontSize="{StaticResource FontSizeMono}"
+                             TextWrapping="NoWrap"/>
+                </Grid>
+              </Border>
+            </DataTemplate>
+          </ItemsControl.ItemTemplate>
+        </ItemsControl>
+        </ScrollViewer>
       </Grid>
     </Grid>
-  </Border>
+  </ctl:ModalShell>
 </Window>
diff --git a/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml.cs b/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml.cs
index a2454c0..9cd866f 100644
--- a/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml.cs
+++ b/src/ClaudeDo.Ui/Views/Modals/DiffModalView.axaml.cs
@@ -2,7 +2,6 @@ using Avalonia;
 using Avalonia.Animation;
 using Avalonia.Animation.Easings;
 using Avalonia.Controls;
-using Avalonia.Input;
 using Avalonia.Media;
 using Avalonia.Styling;
 using ClaudeDo.Ui.ViewModels.Modals;
@@ -43,10 +42,4 @@ public partial class DiffModalView : Window
         Opacity = 1;
         RenderTransform = new ScaleTransform(1.0, 1.0);
     }
-
-    private void TitleBar_PointerPressed(object? sender, PointerPressedEventArgs e)
-    {
-        if (e.GetCurrentPoint(this).Properties.IsLeftButtonPressed)
-            BeginMoveDrag(e);
-    }
 }