diff --git a/src/Ursa/Controls/Dialog/Dialog.cs b/src/Ursa/Controls/Dialog/Dialog.cs
index 15d7ed5..9922f15 100644
--- a/src/Ursa/Controls/Dialog/Dialog.cs
+++ b/src/Ursa/Controls/Dialog/Dialog.cs
@@ -216,7 +216,8 @@ public static class Dialog
         }
         if (!string.IsNullOrWhiteSpace(options.StyleClass))
         {
-            window.Classes.Add(options.StyleClass);
+            var styles = options.StyleClass!.Split([' '], StringSplitOptions.RemoveEmptyEntries);
+            window.Classes.AddRange(styles);
         }
     }
 
@@ -246,7 +247,8 @@ public static class Dialog
         }
         if (!string.IsNullOrWhiteSpace(options.StyleClass))
         {
-            window.Classes.Add(options.StyleClass);
+            var styles = options.StyleClass!.Split([' '], StringSplitOptions.RemoveEmptyEntries);
+            window.Classes.AddRange(styles);
         }
     }
 }
\ No newline at end of file
diff --git a/src/Ursa/Controls/Dialog/OverlayDialog.cs b/src/Ursa/Controls/Dialog/OverlayDialog.cs
index 15bd7eb..6028f83 100644
--- a/src/Ursa/Controls/Dialog/OverlayDialog.cs
+++ b/src/Ursa/Controls/Dialog/OverlayDialog.cs
@@ -207,7 +207,8 @@ public static class OverlayDialog
         control.CanResize = options.CanResize;
         if (!string.IsNullOrWhiteSpace(options.StyleClass))
         {
-            control.Classes.Add(options.StyleClass);
+            var styles = options.StyleClass!.Split([' '], StringSplitOptions.RemoveEmptyEntries);
+            control.Classes.AddRange(styles);
         }
         DialogControlBase.SetCanDragMove(control, options.CanDragMove);
     }
@@ -237,7 +238,8 @@ public static class OverlayDialog
         control.CanResize = options.CanResize;
         if (!string.IsNullOrWhiteSpace(options.StyleClass))
         {
-            control.Classes.Add(options.StyleClass);
+            var styles = options.StyleClass!.Split([' '], StringSplitOptions.RemoveEmptyEntries);
+            control.Classes.AddRange(styles);
         }
         DialogControlBase.SetCanDragMove(control, options.CanDragMove);
     }
diff --git a/src/Ursa/Controls/Drawer/Drawer.cs b/src/Ursa/Controls/Drawer/Drawer.cs
index 4deaeaa..2bc3340 100644
--- a/src/Ursa/Controls/Drawer/Drawer.cs
+++ b/src/Ursa/Controls/Drawer/Drawer.cs
@@ -220,7 +220,8 @@ public static class Drawer
 
         if (!string.IsNullOrWhiteSpace(options.StyleClass))
         {
-            drawer.Classes.Add(options.StyleClass!);
+            var styles = options.StyleClass!.Split([' '], StringSplitOptions.RemoveEmptyEntries);
+            drawer.Classes.AddRange(styles);
         }
     }
 
@@ -246,7 +247,8 @@ public static class Drawer
         }
         if (!string.IsNullOrWhiteSpace(options.StyleClass))
         {
-            drawer.Classes.Add(options.StyleClass!);
+            var styles = options.StyleClass!.Split([' '], StringSplitOptions.RemoveEmptyEntries);
+            drawer.Classes.AddRange(styles);
         }
     }
 }
\ No newline at end of file
diff --git a/src/Ursa/Controls/MessageBox/MessageBox.cs b/src/Ursa/Controls/MessageBox/MessageBox.cs
index 86c059b..14c6c8a 100644
--- a/src/Ursa/Controls/MessageBox/MessageBox.cs
+++ b/src/Ursa/Controls/MessageBox/MessageBox.cs
@@ -22,7 +22,8 @@ public static class MessageBox
         };
         if (!string.IsNullOrWhiteSpace(styleClass))
         {
-            messageWindow.Classes.Add(styleClass!);
+            var styles = styleClass!.Split([' '], StringSplitOptions.RemoveEmptyEntries);
+            messageWindow.Classes.AddRange(styles);
         }
         var lifetime = Application.Current?.ApplicationLifetime;
         if (lifetime is not IClassicDesktopStyleApplicationLifetime classLifetime) return MessageBoxResult.None;
@@ -53,7 +54,8 @@ public static class MessageBox
         };
         if (!string.IsNullOrWhiteSpace(styleClass))
         {
-            messageWindow.Classes.Add(styleClass!);
+            var styles = styleClass!.Split([' '], StringSplitOptions.RemoveEmptyEntries);
+            messageWindow.Classes.AddRange(styles!);
         }
         var result = await messageWindow.ShowDialog<MessageBoxResult>(owner);
         return result;
@@ -80,7 +82,8 @@ public static class MessageBox
         };
         if (!string.IsNullOrWhiteSpace(styleClass))
         {
-            messageControl.Classes.Add(styleClass!);
+            var styles = styleClass!.Split([' '], StringSplitOptions.RemoveEmptyEntries);
+            messageControl.Classes.AddRange(styles!);
         }
         host.AddModalDialog(messageControl);
         var result = await messageControl.ShowAsync<MessageBoxResult>();
diff --git a/src/Ursa/Controls/OverlayShared/OverlayDialogManager.cs b/src/Ursa/Controls/OverlayShared/OverlayDialogManager.cs
index 685d690..ba87b7a 100644
--- a/src/Ursa/Controls/OverlayShared/OverlayDialogManager.cs
+++ b/src/Ursa/Controls/OverlayShared/OverlayDialogManager.cs
@@ -1,4 +1,5 @@
 using System.Collections.Concurrent;
+using System.Diagnostics;
 
 namespace Ursa.Controls;
 
@@ -10,6 +11,7 @@ internal static class OverlayDialogManager
     
     public static void RegisterHost(OverlayDialogHost host, string? id, int? hash)
     {
+        Debug.WriteLine("Count: "+Hosts.Count);
         Hosts.TryAdd(new HostKey(id, hash), host);
     }
     
diff --git a/src/Ursa/Ursa.csproj b/src/Ursa/Ursa.csproj
index 190bae4..fda6393 100644
--- a/src/Ursa/Ursa.csproj
+++ b/src/Ursa/Ursa.csproj
@@ -15,8 +15,8 @@
 
     <ItemGroup>
         <PackageReference Include="Avalonia" Version="$(AvaloniaVersion)"/>
-        <PackageReference Include="Irihi.Avalonia.Shared" Version="0.2.0" />
-        <PackageReference Include="Irihi.Avalonia.Shared.Contracts" Version="0.2.0" />
+        <PackageReference Include="Irihi.Avalonia.Shared" Version="0.2.1" />
+        <PackageReference Include="Irihi.Avalonia.Shared.Contracts" Version="0.2.1" />
     </ItemGroup>
 
     <ItemGroup>
diff --git a/tests/HeadlessTest.Ursa/Controls/DialogTests/StyleClassTests/StyleClassTests.cs b/tests/HeadlessTest.Ursa/Controls/DialogTests/StyleClassTests/StyleClassTests.cs
index bfcc733..389912d 100644
--- a/tests/HeadlessTest.Ursa/Controls/DialogTests/StyleClassTests/StyleClassTests.cs
+++ b/tests/HeadlessTest.Ursa/Controls/DialogTests/StyleClassTests/StyleClassTests.cs
@@ -1,7 +1,9 @@
 using Avalonia.Controls;
 using Avalonia.Headless.XUnit;
+using Avalonia.Threading;
 using Avalonia.VisualTree;
 using Ursa.Controls;
+using Xunit;
 
 namespace HeadlessTest.Ursa.Controls.DialogTests.StyleClassTests;
 
@@ -16,7 +18,8 @@ public class StyleClassTests
             DataContext = vm,
         };
         ursaWindow.Show();
-        vm.InvokeDialog();
+        vm.InvokeDialog("Custom", ursaWindow.GetHashCode());
+        Dispatcher.UIThread.RunJobs();
         var dialog = ursaWindow.GetVisualDescendants().OfType<DefaultDialogControl>().SingleOrDefault();
         Assert.NotNull(dialog);
         Assert.Contains("Custom", dialog.Classes);
@@ -26,5 +29,58 @@ public class StyleClassTests
         var cancelButton = dialog.GetVisualDescendants().OfType<Button>().SingleOrDefault(a=>a.Name == DefaultDialogControl.PART_CancelButton);
         Assert.NotNull(cancelButton);
         Assert.Equal("取消", cancelButton.Content);
+        ursaWindow.Close();
+        Dispatcher.UIThread.RunJobs();
+    }
+    
+    [AvaloniaFact]
+    public void StyleClass_Changes_Button_Content_With_Multiple_Classes()
+    {
+        var vm = new TestViewModel();
+        var ursaWindow = new TestWindow()
+        {
+            DataContext = vm,
+        };
+        ursaWindow.Show();
+        vm.InvokeDialog("Custom Custom2", ursaWindow.GetHashCode());
+        Dispatcher.UIThread.RunJobs();
+        var dialog = ursaWindow.GetVisualDescendants().OfType<DefaultDialogControl>().SingleOrDefault();
+        Assert.NotNull(dialog);
+        Assert.Contains("Custom", dialog.Classes);
+        Assert.Contains("Custom2", dialog.Classes);
+        var okButton = dialog.GetVisualDescendants().OfType<Button>().SingleOrDefault(a=>a.Name == DefaultDialogControl.PART_OKButton);
+        Assert.NotNull(okButton);
+        Assert.Equal("CUSTOM", okButton.Content);
+        Assert.Contains("Warning", okButton.Classes);
+        Assert.Contains("Small", okButton.Classes);
+        var cancelButton = dialog.GetVisualDescendants().OfType<Button>().SingleOrDefault(a=>a.Name == DefaultDialogControl.PART_CancelButton);
+        Assert.NotNull(cancelButton);
+        Assert.Equal("取消", cancelButton.Content);
+        ursaWindow.Close();
+        Dispatcher.UIThread.RunJobs();
+    }
+    
+    [AvaloniaFact]
+    public void StyleClass_Changes_Button_Content_With_No_StyleClass()
+    {
+        var vm = new TestViewModel();
+        var ursaWindow = new TestWindow()
+        {
+            DataContext = vm,
+        };
+        ursaWindow.Show();
+        vm.InvokeDialog(null, ursaWindow.GetHashCode());
+        Dispatcher.UIThread.RunJobs();
+        var dialog = ursaWindow.GetVisualDescendants().OfType<DefaultDialogControl>().SingleOrDefault();
+        Assert.NotNull(dialog);
+        Assert.DoesNotContain("Custom", dialog.Classes);
+        var okButton = dialog.GetVisualDescendants().OfType<Button>().SingleOrDefault(a=>a.Name == DefaultDialogControl.PART_OKButton);
+        Assert.NotNull(okButton);
+        Assert.Equal("确认", okButton.Content);
+        var cancelButton = dialog.GetVisualDescendants().OfType<Button>().SingleOrDefault(a=>a.Name == DefaultDialogControl.PART_CancelButton);
+        Assert.NotNull(cancelButton);
+        Assert.Equal("取消", cancelButton.Content);
+        ursaWindow.Close();
+        Dispatcher.UIThread.RunJobs();
     }
 }
\ No newline at end of file
diff --git a/tests/HeadlessTest.Ursa/Controls/DialogTests/StyleClassTests/TestViewModel.cs b/tests/HeadlessTest.Ursa/Controls/DialogTests/StyleClassTests/TestViewModel.cs
index 7e7ffce..3b46e66 100644
--- a/tests/HeadlessTest.Ursa/Controls/DialogTests/StyleClassTests/TestViewModel.cs
+++ b/tests/HeadlessTest.Ursa/Controls/DialogTests/StyleClassTests/TestViewModel.cs
@@ -6,12 +6,13 @@ namespace HeadlessTest.Ursa.Controls.DialogTests.StyleClassTests;
 
 public class TestViewModel: ObservableObject
 {
-    public void InvokeDialog()
+    public void InvokeDialog(string? classes, int? hash)
     {
         OverlayDialog.Show<TextBlock, string>("Hello World", options: new OverlayDialogOptions()
         {
             Buttons = DialogButton.OKCancel,
-            StyleClass = "Custom",
+            StyleClass = classes,
+            TopLevelHashCode = hash,
         });
     }
 }
\ No newline at end of file
diff --git a/tests/HeadlessTest.Ursa/Controls/DialogTests/StyleClassTests/TestWindow.axaml b/tests/HeadlessTest.Ursa/Controls/DialogTests/StyleClassTests/TestWindow.axaml
index 8cabc42..72534bb 100644
--- a/tests/HeadlessTest.Ursa/Controls/DialogTests/StyleClassTests/TestWindow.axaml
+++ b/tests/HeadlessTest.Ursa/Controls/DialogTests/StyleClassTests/TestWindow.axaml
@@ -3,6 +3,7 @@
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
         xmlns:u="https://irihi.tech/ursa"
+        xmlns:helpers="clr-namespace:Irihi.Avalonia.Shared.Helpers;assembly=Irihi.Avalonia.Shared"
         mc:Ignorable="d" d:DesignWidth="800"
         d:DesignHeight="450"
         x:Class="HeadlessTest.Ursa.Controls.DialogTests.StyleClassTests.TestWindow"
@@ -13,6 +14,11 @@
                 <Setter Property="Content" Value="CUSTOM"/>
             </Style>
         </Style>
+        <Style Selector="u|DefaultDialogControl.Custom2">
+            <Style Selector="^ /template/ Button#PART_OKButton">
+                <Setter Property="helpers:ClassHelper.Classes" Value="Warning Small" />
+            </Style>
+        </Style>
     </u:UrsaWindow.Styles>
     Welcome to Avalonia!