diff --git a/samples/ControlCatalog/App.xaml.cs b/samples/ControlCatalog/App.xaml.cs
index eb8ecc3af0..e936359fe4 100644
--- a/samples/ControlCatalog/App.xaml.cs
+++ b/samples/ControlCatalog/App.xaml.cs
@@ -23,9 +23,9 @@ namespace ControlCatalog
             Source = new Uri("avares://Avalonia.Controls.ColorPicker/Themes/Fluent/Fluent.xaml")
         };
 
-        public static readonly StyleInclude ColorPickerDefault = new StyleInclude(new Uri("avares://ControlCatalog/Styles"))
+        public static readonly StyleInclude ColorPickerSimple = new StyleInclude(new Uri("avares://ControlCatalog/Styles"))
         {
-            Source = new Uri("avares://Avalonia.Controls.ColorPicker/Themes/Default/Default.xaml")
+            Source = new Uri("avares://Avalonia.Controls.ColorPicker/Themes/Simple/Simple.xaml")
         };
 
         public static readonly StyleInclude DataGridFluent = new StyleInclude(new Uri("avares://ControlCatalog/Styles"))
@@ -33,16 +33,16 @@ namespace ControlCatalog
             Source = new Uri("avares://Avalonia.Controls.DataGrid/Themes/Fluent.xaml")
         };
 
-        public static readonly StyleInclude DataGridDefault = new StyleInclude(new Uri("avares://ControlCatalog/Styles"))
+        public static readonly StyleInclude DataGridSimple = new StyleInclude(new Uri("avares://ControlCatalog/Styles"))
         {
-            Source = new Uri("avares://Avalonia.Controls.DataGrid/Themes/Default.xaml")
+            Source = new Uri("avares://Avalonia.Controls.DataGrid/Themes/Simple.xaml")
         };
 
         public static FluentTheme Fluent = new FluentTheme(new Uri("avares://ControlCatalog/Styles"));
 
-        public static SimpleTheme Default = new SimpleTheme(new Uri("avares://ControlCatalog/Styles"));
+        public static SimpleTheme Simple = new SimpleTheme(new Uri("avares://ControlCatalog/Styles"));
 
-        public static Styles DefaultLight = new Styles
+        public static Styles SimpleLight = new Styles
         {
             new StyleInclude(new Uri("resm:Styles?assembly=ControlCatalog"))
             {
@@ -56,10 +56,10 @@ namespace ControlCatalog
             {
                 Source = new Uri("avares://Avalonia.Themes.Fluent/Accents/BaseLight.xaml")
             },
-            Default
+            Simple
         };
 
-        public static Styles DefaultDark = new Styles
+        public static Styles SimpleDark = new Styles
         {
             new StyleInclude(new Uri("resm:Styles?assembly=ControlCatalog"))
             {
@@ -73,14 +73,14 @@ namespace ControlCatalog
             {
                 Source = new Uri("avares://Avalonia.Themes.Fluent/Accents/BaseDark.xaml")
             },
-            Default
+            Simple
         };
 
         public override void Initialize()
         {
-            Styles.Insert(0, Fluent);
-            Styles.Insert(1, ColorPickerFluent);
-            Styles.Insert(2, DataGridFluent);
+            Styles.Insert(0, Simple);
+            Styles.Insert(1, ColorPickerSimple);
+            Styles.Insert(2, DataGridSimple);
             AvaloniaXamlLoader.Load(this);
         }
 
diff --git a/samples/ControlCatalog/MainView.xaml b/samples/ControlCatalog/MainView.xaml
index 7461e78c33..7f5a191519 100644
--- a/samples/ControlCatalog/MainView.xaml
+++ b/samples/ControlCatalog/MainView.xaml
@@ -187,8 +187,8 @@
               <ComboBox.Items>
                 <models:CatalogTheme>FluentLight</models:CatalogTheme>
                 <models:CatalogTheme>FluentDark</models:CatalogTheme>
-                <models:CatalogTheme>DefaultLight</models:CatalogTheme>
-                <models:CatalogTheme>DefaultDark</models:CatalogTheme>
+                <models:CatalogTheme>SimpleLight</models:CatalogTheme>
+                <models:CatalogTheme>SimpleDark</models:CatalogTheme>
               </ComboBox.Items>
             </ComboBox>
             <ComboBox x:Name="TransparencyLevels"
diff --git a/samples/ControlCatalog/MainView.xaml.cs b/samples/ControlCatalog/MainView.xaml.cs
index d8d58edaf6..58433f13ce 100644
--- a/samples/ControlCatalog/MainView.xaml.cs
+++ b/samples/ControlCatalog/MainView.xaml.cs
@@ -58,19 +58,19 @@ namespace ControlCatalog
                         Application.Current.Styles[1] = App.ColorPickerFluent;
                         Application.Current.Styles[2] = App.DataGridFluent;
                     }
-                    else if (theme == CatalogTheme.DefaultLight)
+                    else if (theme == CatalogTheme.SimpleLight)
                     {
-                        App.Default.Mode = Avalonia.Themes.Simple.SimpleThemeMode.Light;
-                        Application.Current.Styles[0] = App.DefaultLight;
-                        Application.Current.Styles[1] = App.ColorPickerDefault;
-                        Application.Current.Styles[2] = App.DataGridDefault;
+                        App.Simple.Mode = Avalonia.Themes.Simple.SimpleThemeMode.Light;
+                        Application.Current.Styles[0] = App.SimpleLight;
+                        Application.Current.Styles[1] = App.ColorPickerSimple;
+                        Application.Current.Styles[2] = App.DataGridSimple;
                     }
-                    else if (theme == CatalogTheme.DefaultDark)
+                    else if (theme == CatalogTheme.SimpleDark)
                     {
-                        App.Default.Mode = Avalonia.Themes.Simple.SimpleThemeMode.Dark;
-                        Application.Current.Styles[0] = App.DefaultDark;
-                        Application.Current.Styles[1] = App.ColorPickerDefault;
-                        Application.Current.Styles[2] = App.DataGridDefault;
+                        App.Simple.Mode = Avalonia.Themes.Simple.SimpleThemeMode.Dark;
+                        Application.Current.Styles[0] = App.SimpleDark;
+                        Application.Current.Styles[1] = App.ColorPickerSimple;
+                        Application.Current.Styles[2] = App.DataGridSimple;
                     }
                 }
             };
diff --git a/samples/ControlCatalog/Models/CatalogTheme.cs b/samples/ControlCatalog/Models/CatalogTheme.cs
index f7be8e0014..37224ed26e 100644
--- a/samples/ControlCatalog/Models/CatalogTheme.cs
+++ b/samples/ControlCatalog/Models/CatalogTheme.cs
@@ -1,14 +1,10 @@
-using System;
-using System.Collections.Generic;
-using System.Text;
-
-namespace ControlCatalog.Models
+namespace ControlCatalog.Models
 {
     public enum CatalogTheme
     {
         FluentLight,
         FluentDark,
-        DefaultLight,
-        DefaultDark
+        SimpleLight,
+        SimpleDark
     }
 }
diff --git a/src/Avalonia.Controls.ColorPicker/Themes/Default/ColorPreviewer.xaml b/src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorPreviewer.xaml
similarity index 100%
rename from src/Avalonia.Controls.ColorPicker/Themes/Default/ColorPreviewer.xaml
rename to src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorPreviewer.xaml
diff --git a/src/Avalonia.Controls.ColorPicker/Themes/Default/ColorSlider.xaml b/src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorSlider.xaml
similarity index 100%
rename from src/Avalonia.Controls.ColorPicker/Themes/Default/ColorSlider.xaml
rename to src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorSlider.xaml
diff --git a/src/Avalonia.Controls.ColorPicker/Themes/Default/ColorSpectrum.xaml b/src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorSpectrum.xaml
similarity index 100%
rename from src/Avalonia.Controls.ColorPicker/Themes/Default/ColorSpectrum.xaml
rename to src/Avalonia.Controls.ColorPicker/Themes/Simple/ColorSpectrum.xaml
diff --git a/src/Avalonia.Controls.ColorPicker/Themes/Default/Default.xaml b/src/Avalonia.Controls.ColorPicker/Themes/Simple/Simple.xaml
similarity index 94%
rename from src/Avalonia.Controls.ColorPicker/Themes/Default/Default.xaml
rename to src/Avalonia.Controls.ColorPicker/Themes/Simple/Simple.xaml
index b452e34394..697a94421d 100644
--- a/src/Avalonia.Controls.ColorPicker/Themes/Default/Default.xaml
+++ b/src/Avalonia.Controls.ColorPicker/Themes/Simple/Simple.xaml
@@ -36,9 +36,9 @@
       <ResourceDictionary.MergedDictionaries>
 
         <!-- Primitives -->
-        <ResourceInclude Source="avares://Avalonia.Controls.ColorPicker/Themes/Default/ColorPreviewer.xaml" />
-        <ResourceInclude Source="avares://Avalonia.Controls.ColorPicker/Themes/Default/ColorSlider.xaml" />
-        <ResourceInclude Source="avares://Avalonia.Controls.ColorPicker/Themes/Default/ColorSpectrum.xaml" />
+        <ResourceInclude Source="avares://Avalonia.Controls.ColorPicker/Themes/Simple/ColorPreviewer.xaml" />
+        <ResourceInclude Source="avares://Avalonia.Controls.ColorPicker/Themes/Simple/ColorSlider.xaml" />
+        <ResourceInclude Source="avares://Avalonia.Controls.ColorPicker/Themes/Simple/ColorSpectrum.xaml" />
 
         <!-- Controls -->
         <!-- Note the ColorPicker and ColorView are unsupported in the default theme -->
diff --git a/src/Avalonia.Controls.DataGrid/Themes/Default.xaml b/src/Avalonia.Controls.DataGrid/Themes/Simple.xaml
similarity index 99%
rename from src/Avalonia.Controls.DataGrid/Themes/Default.xaml
rename to src/Avalonia.Controls.DataGrid/Themes/Simple.xaml
index 83d9332613..6a748f399e 100644
--- a/src/Avalonia.Controls.DataGrid/Themes/Default.xaml
+++ b/src/Avalonia.Controls.DataGrid/Themes/Simple.xaml
@@ -223,7 +223,7 @@
       </Style>
     </ControlTheme>
 
-    <ControlTheme x:Key="DefaultDataGridRowGroupExpanderButtonTheme"
+    <ControlTheme x:Key="SimpleDataGridRowGroupExpanderButtonTheme"
                   TargetType="ToggleButton">
       <Setter Property="Template">
         <ControlTemplate>
@@ -270,7 +270,7 @@
                           BorderThickness="{TemplateBinding BorderThickness}"
                           CornerRadius="{TemplateBinding CornerRadius}"
                           Foreground="{TemplateBinding Foreground}"
-                          Theme="{StaticResource DefaultDataGridRowGroupExpanderButtonTheme}" />
+                          Theme="{StaticResource SimpleDataGridRowGroupExpanderButtonTheme}" />
 
             <StackPanel Grid.Row="1"
                         Grid.Column="3"
diff --git a/src/Avalonia.Diagnostics/Diagnostics/Views/MainWindow.xaml b/src/Avalonia.Diagnostics/Diagnostics/Views/MainWindow.xaml
index 63073952ac..1270dbaa62 100644
--- a/src/Avalonia.Diagnostics/Diagnostics/Views/MainWindow.xaml
+++ b/src/Avalonia.Diagnostics/Diagnostics/Views/MainWindow.xaml
@@ -2,7 +2,6 @@
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:views="clr-namespace:Avalonia.Diagnostics.Views"
         xmlns:diag="clr-namespace:Avalonia.Diagnostics"
-        xmlns:default="using:Avalonia.Themes.Simple"
         Title="Avalonia DevTools"
         x:Class="Avalonia.Diagnostics.Views.MainWindow"
         Theme="{StaticResource {x:Type Window}}">
@@ -11,8 +10,8 @@
   </Window.DataTemplates>
   
   <Window.Styles>
-    <default:SimpleTheme Mode="Light"/>
-    <StyleInclude Source="avares://Avalonia.Controls.DataGrid/Themes/Default.xaml"/>
+    <SimpleTheme Mode="Light"/>
+    <StyleInclude Source="avares://Avalonia.Controls.DataGrid/Themes/Simple.xaml"/>
     <StyleInclude Source="avares://Avalonia.Diagnostics/Diagnostics/Controls/ThicknessEditor.axaml" />
     <StyleInclude Source="avares://Avalonia.Diagnostics/Diagnostics/Controls/FilterTextBox.axaml" />
   </Window.Styles>