diff --git a/src/ClaudeDo.Ui/Views/Controls/ModalShell.axaml b/src/ClaudeDo.Ui/Views/Controls/ModalShell.axaml
index c44ceb45..55488e90 100644
--- a/src/ClaudeDo.Ui/Views/Controls/ModalShell.axaml
+++ b/src/ClaudeDo.Ui/Views/Controls/ModalShell.axaml
@@ -1,6 +1,7 @@
 <ResourceDictionary xmlns="https://github.com/avaloniaui"
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-                    xmlns:ctl="using:ClaudeDo.Ui.Views.Controls">
+                    xmlns:ctl="using:ClaudeDo.Ui.Views.Controls"
+                    xmlns:cconv="using:ClaudeDo.Ui.Converters">
   <ControlTheme x:Key="{x:Type ctl:ModalShell}" TargetType="ctl:ModalShell">
     <Setter Property="Template">
       <ControlTemplate>
@@ -26,12 +27,15 @@
                 <Button Name="PART_MaxButton" Grid.Column="2" Classes="icon-btn"
                         IsVisible="{TemplateBinding ShowMaximizeButton}"
                         VerticalAlignment="Center">
-                  <PathIcon Name="PART_MaxIcon" Data="{StaticResource Icon.WinMax}" Width="10" Height="10"/>
+                  <PathIcon Name="PART_MaxIcon" Width="14" Height="14"
+                            Data="{Binding Source='mdi:WindowMaximize', Converter={x:Static cconv:IconKeyConverter.Instance}}"/>
                 </Button>
-                <Button Grid.Column="3" Classes="icon-btn" Content="✕"
-                        FontSize="{DynamicResource FontSizeBody}"
+                <Button Grid.Column="3" Classes="icon-btn"
                         Command="{TemplateBinding CloseCommand}"
-                        VerticalAlignment="Center"/>
+                        VerticalAlignment="Center">
+                  <PathIcon Width="14" Height="14"
+                            Data="{Binding Source='mdi:WindowClose', Converter={x:Static cconv:IconKeyConverter.Instance}}"/>
+                </Button>
               </Grid>
             </Border>
             <Border Name="PART_Footer" DockPanel.Dock="Bottom"
diff --git a/src/ClaudeDo.Ui/Views/Controls/ModalShell.axaml.cs b/src/ClaudeDo.Ui/Views/Controls/ModalShell.axaml.cs
index 8b9d00b1..187554c2 100644
--- a/src/ClaudeDo.Ui/Views/Controls/ModalShell.axaml.cs
+++ b/src/ClaudeDo.Ui/Views/Controls/ModalShell.axaml.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Windows.Input;
 using Avalonia;
 using Avalonia.Controls;
@@ -5,6 +6,7 @@ using Avalonia.Controls.Primitives;
 using Avalonia.Input;
 using Avalonia.Interactivity;
 using Avalonia.Media;
+using ClaudeDo.Ui.Converters;
 
 namespace ClaudeDo.Ui.Views.Controls;
 
@@ -84,9 +86,8 @@ public class ModalShell : ContentControl
     {
         if (_maxIcon is null || _window is null) return;
         var maximized = _window.WindowState == WindowState.Maximized;
-        var key = maximized ? "Icon.WinRestore" : "Icon.WinMax";
-        if (this.TryFindResource(key, out var geometry) && geometry is Geometry g)
-            _maxIcon.Data = g;
+        _maxIcon.Data = (Geometry?)IconKeyConverter.Instance.Convert(
+            maximized ? "mdi:WindowRestore" : "mdi:WindowMaximize", typeof(Geometry), null, CultureInfo.InvariantCulture);
         if (_maxButton is not null)
         {
             var tipKey = maximized ? "modals.diff.restore" : "modals.diff.maximize";
diff --git a/src/ClaudeDo.Ui/Views/MainWindow.axaml b/src/ClaudeDo.Ui/Views/MainWindow.axaml
index a053c0ab..63f2bdfd 100644
--- a/src/ClaudeDo.Ui/Views/MainWindow.axaml
+++ b/src/ClaudeDo.Ui/Views/MainWindow.axaml
@@ -115,16 +115,16 @@
           <Button Classes="title-ctrl"
                   Command="{Binding OpenMissionControlCommand}"
                   ToolTip.Tip="{loc:Tr missionControl.windowTitle}">
-            <PathIcon Data="{StaticResource Icon.Grid}" Width="12" Height="12"/>
+            <PathIcon Width="14" Height="14" Data="{Binding Source='mdi:ViewGridOutline', Converter={StaticResource IconKey}}"/>
           </Button>
           <Button Classes="title-ctrl" Click="OnMinimize">
-            <PathIcon Data="{StaticResource Icon.WinMin}" Width="10" Height="10"/>
+            <PathIcon Width="14" Height="14" Data="{Binding Source='mdi:WindowMinimize', Converter={StaticResource IconKey}}"/>
           </Button>
           <Button Classes="title-ctrl" Click="OnToggleMax">
-            <PathIcon x:Name="MaxIcon" Data="{StaticResource Icon.WinMax}" Width="10" Height="10"/>
+            <PathIcon x:Name="MaxIcon" Width="14" Height="14" Data="{Binding Source='mdi:WindowMaximize', Converter={StaticResource IconKey}}"/>
           </Button>
           <Button Classes="title-ctrl close" Click="OnClose">
-            <PathIcon Data="{StaticResource Icon.WinClose}" Width="10" Height="10"/>
+            <PathIcon Width="14" Height="14" Data="{Binding Source='mdi:WindowClose', Converter={StaticResource IconKey}}"/>
           </Button>
         </StackPanel>
 
diff --git a/src/ClaudeDo.Ui/Views/MainWindow.axaml.cs b/src/ClaudeDo.Ui/Views/MainWindow.axaml.cs
index b1633f86..34985876 100644
--- a/src/ClaudeDo.Ui/Views/MainWindow.axaml.cs
+++ b/src/ClaudeDo.Ui/Views/MainWindow.axaml.cs
@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Linq;
 using System.Threading.Tasks;
 using Avalonia;
@@ -5,6 +6,7 @@ using Avalonia.Controls;
 using Avalonia.Input;
 using Avalonia.Layout;
 using Avalonia.Media;
+using ClaudeDo.Ui.Converters;
 using ClaudeDo.Ui.Localization;
 using ClaudeDo.Ui.Services;
 using ClaudeDo.Ui.ViewModels;
@@ -64,9 +66,8 @@ public partial class MainWindow : Window
 
     private void UpdateMaxIcon()
     {
-        var key = WindowState == WindowState.Maximized ? "Icon.WinRestore" : "Icon.WinMax";
-        if (this.TryFindResource(key, out var geometry) && geometry is Geometry g)
-            MaxIcon.Data = g;
+        MaxIcon.Data = (Geometry?)IconKeyConverter.Instance.Convert(
+            WindowState == WindowState.Maximized ? "mdi:WindowRestore" : "mdi:WindowMaximize", typeof(Geometry), null, CultureInfo.InvariantCulture);
     }
 
     private void OnDataContextChanged(object? sender, EventArgs e)
diff --git a/src/ClaudeDo.Ui/Views/MissionControl/ConPtyPaneView.axaml b/src/ClaudeDo.Ui/Views/MissionControl/ConPtyPaneView.axaml
index c3082576..d7e4984c 100644
--- a/src/ClaudeDo.Ui/Views/MissionControl/ConPtyPaneView.axaml
+++ b/src/ClaudeDo.Ui/Views/MissionControl/ConPtyPaneView.axaml
@@ -44,7 +44,7 @@
           <Button Grid.Column="3" Classes="title-ctrl"
                   Command="{Binding CloseCommand}"
                   ToolTip.Tip="{loc:Tr missionControl.closeSession}">
-            <PathIcon Data="{StaticResource Icon.WinClose}" Width="12" Height="12"/>
+            <PathIcon Width="14" Height="14" Data="{Binding Source='mdi:WindowClose', Converter={StaticResource IconKey}}"/>
           </Button>
         </Grid>
       </Border>
diff --git a/src/ClaudeDo.Ui/Views/MissionControl/MissionControlView.axaml b/src/ClaudeDo.Ui/Views/MissionControl/MissionControlView.axaml
index 15074049..e799e7cb 100644
--- a/src/ClaudeDo.Ui/Views/MissionControl/MissionControlView.axaml
+++ b/src/ClaudeDo.Ui/Views/MissionControl/MissionControlView.axaml
@@ -45,7 +45,7 @@
                                VerticalAlignment="Center"/>
           <Button Classes="icon-btn"
                   ToolTip.Tip="{loc:Tr missionControl.newSession}">
-            <PathIcon Data="{StaticResource Icon.Plus}" Width="15" Height="15"/>
+            <PathIcon Width="16" Height="16" Data="{Binding Source='mdi:Plus', Converter={StaticResource IconKey}}"/>
             <Button.Flyout>
               <MenuFlyout ItemsSource="{Binding SessionTargets}" Opening="OnSessionFlyoutOpening">
                 <MenuFlyout.ItemContainerTheme>
@@ -60,7 +60,7 @@
           </Button>
           <Button x:Name="RecentSessionsButton" Classes="icon-btn"
                   ToolTip.Tip="{loc:Tr missionControl.recentSessions}">
-            <PathIcon Data="{StaticResource Icon.Clock}" Width="15" Height="15"/>
+            <PathIcon Width="16" Height="16" Data="{Binding Source='mdi:ClockOutline', Converter={StaticResource IconKey}}"/>
             <Button.Flyout>
               <Flyout Placement="BottomEdgeAlignedRight" ShowMode="Standard" Opening="OnRecentSessionsFlyoutOpening">
                 <StackPanel Width="380" Spacing="8" Margin="4">
@@ -136,12 +136,12 @@
           <Button Classes="icon-btn"
                   Command="{Binding ToggleLayoutCommand}"
                   ToolTip.Tip="{Binding LayoutToggleLabel}">
-            <PathIcon Data="{StaticResource Icon.Grid}" Width="15" Height="15"/>
+            <PathIcon Width="16" Height="16" Data="{Binding Source='mdi:ViewGridOutline', Converter={StaticResource IconKey}}"/>
           </Button>
           <Button Classes="icon-btn"
                   Command="{Binding OpenSettingsCommand}"
                   ToolTip.Tip="{loc:Tr missionControl.settings}">
-            <PathIcon Data="{StaticResource Icon.Settings}" Width="15" Height="15"/>
+            <PathIcon Width="16" Height="16" Data="{Binding Source='mdi:Cog', Converter={StaticResource IconKey}}"/>
           </Button>
         </StackPanel>
       </Grid>