diff --git a/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesDark.xaml b/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesDark.xaml
index c6e3259b27..60d83a3ecf 100644
--- a/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesDark.xaml
+++ b/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesDark.xaml
@@ -307,31 +307,29 @@
 
     <!-- Resources for Expander.xaml -->
     <!-- Expander:Header -->
-    <StaticResource x:Key="ExpanderHeaderBackground" ResourceKey="CardBackgroundFillColorDefaultBrush" />
-    <StaticResource x:Key="ExpanderHeaderForeground" ResourceKey="TextFillColorPrimaryBrush" />
-    <StaticResource x:Key="ExpanderHeaderForegroundPointerOver" ResourceKey="TextFillColorPrimaryBrush" />
-    <StaticResource x:Key="ExpanderHeaderForegroundPressed" ResourceKey="TextFillColorPrimaryBrush" />
-    <StaticResource x:Key="ExpanderHeaderBorderBrush" ResourceKey="CardStrokeColorDefaultBrush" />
-    <StaticResource x:Key="ExpanderHeaderBorderPointerOverBrush" ResourceKey="CardStrokeColorDefaultBrush" />
-    <StaticResource x:Key="ExpanderHeaderBorderPressedBrush" ResourceKey="CardStrokeColorDefaultBrush" />
-    <StaticResource x:Key="ExpanderHeaderDisabledForeground" ResourceKey="TextFillColorDisabledBrush" />
-    <StaticResource x:Key="ExpanderHeaderDisabledBorderBrush" ResourceKey="CardStrokeColorDefaultBrush" />
-    <Thickness x:Key="ExpanderHeaderBorderThickness">1</Thickness>
-            
-    <StaticResource x:Key="ExpanderChevronBackground" ResourceKey="SubtleFillColorTransparentBrush" />
-    <StaticResource x:Key="ExpanderChevronPointerOverBackground" ResourceKey="SubtleFillColorSecondaryBrush" />
-    <StaticResource x:Key="ExpanderChevronPressedBackground" ResourceKey="SubtleFillColorTertiaryBrush" />
-    <StaticResource x:Key="ExpanderChevronForeground" ResourceKey="TextFillColorPrimaryBrush" />
-    <StaticResource x:Key="ExpanderChevronPointerOverForeground" ResourceKey="TextFillColorPrimaryBrush" />
-    <StaticResource x:Key="ExpanderChevronPressedForeground" ResourceKey="TextFillColorPrimaryBrush" />
-    <StaticResource x:Key="ExpanderChevronBorderBrush" ResourceKey="SubtleFillColorTransparentBrush" />
-    <StaticResource x:Key="ExpanderChevronBorderPointerOverBrush" ResourceKey="SubtleFillColorTransparentBrush" />
-    <StaticResource x:Key="ExpanderChevronBorderPressedBrush" ResourceKey="SubtleFillColorTransparentBrush" />
-    <Thickness x:Key="ExpanderChevronBorderThickness">0</Thickness>
+    <StaticResource x:Key="ExpanderHeaderBackground" ResourceKey="SystemAltMediumHighColor" />
+    <StaticResource x:Key="ExpanderHeaderForeground" ResourceKey="SystemBaseHighColor" />
+    <StaticResource x:Key="ExpanderHeaderForegroundPointerOver" ResourceKey="SystemBaseHighColor" />
+    <StaticResource x:Key="ExpanderHeaderForegroundPressed" ResourceKey="SystemBaseHighColor" />
+    <StaticResource x:Key="ExpanderHeaderBorderBrush" ResourceKey="SystemBaseLowColor" />
+    <StaticResource x:Key="ExpanderHeaderBorderPointerOverBrush" ResourceKey="SystemBaseLowColor" />
+    <StaticResource x:Key="ExpanderHeaderBorderPressedBrush" ResourceKey="SystemBaseLowColor" />
+    <StaticResource x:Key="ExpanderHeaderDisabledForeground" ResourceKey="SystemControlDisabledChromeDisabledLowBrush" />
+    <StaticResource x:Key="ExpanderHeaderDisabledBorderBrush" ResourceKey="SystemControlDisabledBaseLowBrush" />
+
+    <SolidColorBrush x:Key="ExpanderChevronBackground" Color="Transparent" />
+    <SolidColorBrush x:Key="ExpanderChevronPointerOverBackground" Color="Transparent" />
+    <SolidColorBrush x:Key="ExpanderChevronPressedBackground" Color="Transparent" />
+    <StaticResource x:Key="ExpanderChevronForeground" ResourceKey="SystemBaseHighColor" />
+    <StaticResource x:Key="ExpanderChevronPointerOverForeground" ResourceKey="SystemBaseHighColor" />
+    <StaticResource x:Key="ExpanderChevronPressedForeground" ResourceKey="SystemBaseHighColor" />
+    <SolidColorBrush x:Key="ExpanderChevronBorderBrush" Color="Transparent" />
+    <SolidColorBrush x:Key="ExpanderChevronBorderPointerOverBrush" Color="Transparent" />
+    <SolidColorBrush x:Key="ExpanderChevronBorderPressedBrush" Color="Transparent" />
 
     <!-- Expander:Content -->
-    <StaticResource x:Key="ExpanderContentBackground" ResourceKey="CardBackgroundFillColorSecondaryBrush" />
-    <StaticResource x:Key="ExpanderContentBorderBrush" ResourceKey="CardStrokeColorDefaultBrush" />
+    <StaticResource x:Key="ExpanderContentBackground" ResourceKey="SystemChromeMediumLowColor" />
+    <StaticResource x:Key="ExpanderContentBorderBrush" ResourceKey="SystemBaseLowColor" />
 
     <!--Resources for NotificationCard.xaml -->
     <SolidColorBrush x:Key="NotificationCardBackgroundBrush" Color="#444444" />
diff --git a/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesLight.xaml b/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesLight.xaml
index 808436b9d5..632ffe6ace 100644
--- a/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesLight.xaml
+++ b/src/Avalonia.Themes.Fluent/Accents/FluentControlResourcesLight.xaml
@@ -304,31 +304,29 @@
 
     <!-- Resources for Expander.xaml -->
     <!-- Expander:Header -->
-    <StaticResource x:Key="ExpanderHeaderBackground" ResourceKey="CardBackgroundFillColorDefaultBrush" />
-    <StaticResource x:Key="ExpanderHeaderForeground" ResourceKey="TextFillColorPrimaryBrush" />
-    <StaticResource x:Key="ExpanderHeaderForegroundPointerOver" ResourceKey="TextFillColorPrimaryBrush" />
-    <StaticResource x:Key="ExpanderHeaderForegroundPressed" ResourceKey="TextFillColorPrimaryBrush" />
-    <StaticResource x:Key="ExpanderHeaderBorderBrush" ResourceKey="CardStrokeColorDefaultBrush" />
-    <StaticResource x:Key="ExpanderHeaderBorderPointerOverBrush" ResourceKey="CardStrokeColorDefaultBrush" />
-    <StaticResource x:Key="ExpanderHeaderBorderPressedBrush" ResourceKey="CardStrokeColorDefaultBrush" />
-    <StaticResource x:Key="ExpanderHeaderDisabledForeground" ResourceKey="TextFillColorDisabledBrush" />
-    <StaticResource x:Key="ExpanderHeaderDisabledBorderBrush" ResourceKey="CardStrokeColorDefaultBrush" />
-    <Thickness x:Key="ExpanderHeaderBorderThickness">1</Thickness>
+    <StaticResource x:Key="ExpanderHeaderBackground" ResourceKey="SystemAltMediumHighColor" />
+    <StaticResource x:Key="ExpanderHeaderForeground" ResourceKey="SystemBaseHighColor" />
+    <StaticResource x:Key="ExpanderHeaderForegroundPointerOver" ResourceKey="SystemBaseHighColor" />
+    <StaticResource x:Key="ExpanderHeaderForegroundPressed" ResourceKey="SystemBaseHighColor" />
+    <StaticResource x:Key="ExpanderHeaderBorderBrush" ResourceKey="SystemBaseLowColor" />
+    <StaticResource x:Key="ExpanderHeaderBorderPointerOverBrush" ResourceKey="SystemBaseLowColor" />
+    <StaticResource x:Key="ExpanderHeaderBorderPressedBrush" ResourceKey="SystemBaseLowColor" />
+    <StaticResource x:Key="ExpanderHeaderDisabledForeground" ResourceKey="SystemControlDisabledChromeDisabledLowBrush" />
+    <StaticResource x:Key="ExpanderHeaderDisabledBorderBrush" ResourceKey="SystemControlDisabledBaseLowBrush" />
 
-    <StaticResource x:Key="ExpanderChevronBackground" ResourceKey="SubtleFillColorTransparentBrush" />
-    <StaticResource x:Key="ExpanderChevronPointerOverBackground" ResourceKey="SubtleFillColorSecondaryBrush" />
-    <StaticResource x:Key="ExpanderChevronPressedBackground" ResourceKey="SubtleFillColorTertiaryBrush" />
-    <StaticResource x:Key="ExpanderChevronForeground" ResourceKey="TextFillColorPrimaryBrush" />
-    <StaticResource x:Key="ExpanderChevronPointerOverForeground" ResourceKey="TextFillColorPrimaryBrush" />
-    <StaticResource x:Key="ExpanderChevronPressedForeground" ResourceKey="TextFillColorPrimaryBrush" />
-    <StaticResource x:Key="ExpanderChevronBorderBrush" ResourceKey="SubtleFillColorTransparentBrush" />
-    <StaticResource x:Key="ExpanderChevronBorderPointerOverBrush" ResourceKey="SubtleFillColorTransparentBrush" />
-    <StaticResource x:Key="ExpanderChevronBorderPressedBrush" ResourceKey="SubtleFillColorTransparentBrush" />
-    <Thickness x:Key="ExpanderChevronBorderThickness">0</Thickness>
+    <SolidColorBrush x:Key="ExpanderChevronBackground" Color="Transparent" />
+    <SolidColorBrush x:Key="ExpanderChevronPointerOverBackground" Color="Transparent" />
+    <SolidColorBrush x:Key="ExpanderChevronPressedBackground" Color="Transparent" />
+    <StaticResource x:Key="ExpanderChevronForeground" ResourceKey="SystemBaseHighColor" />
+    <StaticResource x:Key="ExpanderChevronPointerOverForeground" ResourceKey="SystemBaseHighColor" />
+    <StaticResource x:Key="ExpanderChevronPressedForeground" ResourceKey="SystemBaseHighColor" />
+    <SolidColorBrush x:Key="ExpanderChevronBorderBrush" Color="Transparent" />
+    <SolidColorBrush x:Key="ExpanderChevronBorderPointerOverBrush" Color="Transparent" />
+    <SolidColorBrush x:Key="ExpanderChevronBorderPressedBrush" Color="Transparent" />
 
     <!-- Expander:Content -->
-    <StaticResource x:Key="ExpanderContentBackground" ResourceKey="CardBackgroundFillColorSecondaryBrush" />
-    <StaticResource x:Key="ExpanderContentBorderBrush" ResourceKey="CardStrokeColorDefaultBrush" />
+    <StaticResource x:Key="ExpanderContentBackground" ResourceKey="SystemChromeMediumLowColor" />
+    <StaticResource x:Key="ExpanderContentBorderBrush" ResourceKey="SystemBaseLowColor" />
 
     <!--Resources for NotificationCard.xaml -->
     <SolidColorBrush x:Key="NotificationCardBackgroundBrush" Color="White" />
diff --git a/src/Avalonia.Themes.Fluent/Controls/Expander.xaml b/src/Avalonia.Themes.Fluent/Controls/Expander.xaml
index 8606ee16a3..0a61beacae 100644
--- a/src/Avalonia.Themes.Fluent/Controls/Expander.xaml
+++ b/src/Avalonia.Themes.Fluent/Controls/Expander.xaml
@@ -52,14 +52,18 @@
   <HorizontalAlignment x:Key="ExpanderHeaderHorizontalContentAlignment">Stretch</HorizontalAlignment>
   <VerticalAlignment x:Key="ExpanderHeaderVerticalContentAlignment">Center</VerticalAlignment>
   <Thickness x:Key="ExpanderHeaderPadding">16,0,0,0</Thickness>
+  <Thickness x:Key="ExpanderHeaderBorderThickness">1</Thickness>
+  <Thickness x:Key="ExpanderChevronBorderThickness">0</Thickness>
   <Thickness x:Key="ExpanderChevronMargin">20,0,8,0</Thickness>
   <x:Double x:Key="ExpanderChevronButtonSize">32</x:Double>
   <x:Double x:Key="ExpanderChevronGlyphSize">12</x:Double>
 
   <!-- Content -->
   <Thickness x:Key="ExpanderContentPadding">16</Thickness>
-  <Thickness x:Key="ExpanderContentDownBorderThickness">1,0,1,1</Thickness>
+  <Thickness x:Key="ExpanderContentLeftBorderThickness">1,1,0,1</Thickness>
   <Thickness x:Key="ExpanderContentUpBorderThickness">1,1,1,0</Thickness>
+  <Thickness x:Key="ExpanderContentRightBorderThickness">0,1,1,1</Thickness>
+  <Thickness x:Key="ExpanderContentDownBorderThickness">1,0,1,1</Thickness>
 
   <ControlTheme x:Key="FluentExpanderToggleButtonTheme" TargetType="ToggleButton">
     <Setter Property="Padding" Value="{StaticResource ExpanderHeaderPadding}"/>
@@ -274,16 +278,16 @@
     </Style>
 
     <Style Selector="^:left /template/ Border#ExpanderContent">
-      <Setter Property="BorderThickness" Value="{DynamicResource ExpanderDropdownLeftBorderThickness}" />
+      <Setter Property="BorderThickness" Value="{DynamicResource ExpanderContentLeftBorderThickness}" />
     </Style>
     <Style Selector="^:up /template/ Border#ExpanderContent">
-      <Setter Property="BorderThickness" Value="{DynamicResource ExpanderDropdownUpBorderThickness}" />
+      <Setter Property="BorderThickness" Value="{DynamicResource ExpanderContentUpBorderThickness}" />
     </Style>
     <Style Selector="^:right /template/ Border#ExpanderContent">
-      <Setter Property="BorderThickness" Value="{DynamicResource ExpanderDropdownRightBorderThickness}" />
+      <Setter Property="BorderThickness" Value="{DynamicResource ExpanderContentRightBorderThickness}" />
     </Style>
     <Style Selector="^:down /template/ Border#ExpanderContent">
-      <Setter Property="BorderThickness" Value="{DynamicResource ExpanderDropdownDownBorderThickness}" />
+      <Setter Property="BorderThickness" Value="{DynamicResource ExpanderContentDownBorderThickness}" />
     </Style>
   </ControlTheme>
 </ResourceDictionary>