diff --git a/src/AdvancedCalculator.Android/Styles/Android.axaml b/src/AdvancedCalculator.Android/Styles/Android.axaml
index 30f7e04..20622f7 100644
--- a/src/AdvancedCalculator.Android/Styles/Android.axaml
+++ b/src/AdvancedCalculator.Android/Styles/Android.axaml
@@ -1,10 +1,12 @@
-<ResourceDictionary xmlns="https://github.com/avaloniaui"
-                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
-  <!-- Android overrides: larger, touch-first -->
-  <x:Double x:Key="FontSizeBase">16</x:Double>
-  <x:Double x:Key="FontSizeLarge">18</x:Double>
-  <x:Double x:Key="IconSizeM">24</x:Double>
-  <x:Double x:Key="LineHeightBase">1.35</x:Double>
+<Styles xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+  <Styles.Resources>
+    <!-- Android overrides: larger, touch-first -->
+    <x:Double x:Key="FontSizeBase">16</x:Double>
+    <x:Double x:Key="FontSizeLarge">18</x:Double>
+    <x:Double x:Key="IconSizeM">24</x:Double>
+    <x:Double x:Key="LineHeightBase">1.35</x:Double>
+  </Styles.Resources>
 
   <!-- Thin overlay-like scrollbars -->
   <Style Selector="ScrollBar:vertical">
@@ -13,5 +15,4 @@
   <Style Selector="ScrollBar:horizontal">
     <Setter Property="Height" Value="8"/>
   </Style>
-</ResourceDictionary>
-
+</Styles>
diff --git a/src/AdvancedCalculator.Browser/Styles/Browser.axaml b/src/AdvancedCalculator.Browser/Styles/Browser.axaml
index 3842c71..ee701bb 100644
--- a/src/AdvancedCalculator.Browser/Styles/Browser.axaml
+++ b/src/AdvancedCalculator.Browser/Styles/Browser.axaml
@@ -1,9 +1,11 @@
-<ResourceDictionary xmlns="https://github.com/avaloniaui"
-                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
-  <!-- Browser overrides: middle ground -->
-  <x:Double x:Key="FontSizeBase">15</x:Double>
-  <x:Double x:Key="IconSizeM">22</x:Double>
-  <x:Double x:Key="LineHeightBase">1.3</x:Double>
+<Styles xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+  <Styles.Resources>
+    <!-- Browser overrides: middle ground -->
+    <x:Double x:Key="FontSizeBase">15</x:Double>
+    <x:Double x:Key="IconSizeM">22</x:Double>
+    <x:Double x:Key="LineHeightBase">1.3</x:Double>
+  </Styles.Resources>
 
   <!-- Slightly thinner scrollbars on web -->
   <Style Selector="ScrollBar:vertical">
@@ -12,5 +14,4 @@
   <Style Selector="ScrollBar:horizontal">
     <Setter Property="Height" Value="8"/>
   </Style>
-</ResourceDictionary>
-
+</Styles>
diff --git a/src/AdvancedCalculator.Desktop/Styles/Desktop.axaml b/src/AdvancedCalculator.Desktop/Styles/Desktop.axaml
index 7a951d8..c5ac0d9 100644
--- a/src/AdvancedCalculator.Desktop/Styles/Desktop.axaml
+++ b/src/AdvancedCalculator.Desktop/Styles/Desktop.axaml
@@ -1,9 +1,11 @@
-<ResourceDictionary xmlns="https://github.com/avaloniaui"
-                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
-  <!-- Desktop overrides: slightly denser -->
-  <x:Double x:Key="FontSizeBase">13</x:Double>
-  <x:Double x:Key="LineHeightBase">1.2</x:Double>
-  <x:Double x:Key="IconSizeM">20</x:Double>
+<Styles xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+  <Styles.Resources>
+    <!-- Desktop overrides: slightly denser -->
+    <x:Double x:Key="FontSizeBase">13</x:Double>
+    <x:Double x:Key="LineHeightBase">1.2</x:Double>
+    <x:Double x:Key="IconSizeM">20</x:Double>
+  </Styles.Resources>
 
   <!-- Scrollbars a bit thicker on desktop -->
   <Style Selector="ScrollBar:vertical">
@@ -12,5 +14,4 @@
   <Style Selector="ScrollBar:horizontal">
     <Setter Property="Height" Value="12"/>
   </Style>
-</ResourceDictionary>
-
+</Styles>
diff --git a/src/AdvancedCalculator/Converters/IsZeroConverter.cs b/src/AdvancedCalculator/Converters/IsZeroConverter.cs
new file mode 100644
index 0000000..c6d30f8
--- /dev/null
+++ b/src/AdvancedCalculator/Converters/IsZeroConverter.cs
@@ -0,0 +1,25 @@
+using System;
+using System.Globalization;
+using Avalonia.Data.Converters;
+
+namespace AdvancedCalculator.Converters;
+
+public class IsZeroConverter : IValueConverter
+{
+    public static readonly IsZeroConverter Instance = new();
+
+    public object? Convert(object? value, Type targetType, object? parameter, CultureInfo? culture)
+    {
+        if (value is int i)
+            return i == 0;
+        if (value is long l)
+            return l == 0L;
+        if (value is double d)
+            return Math.Abs(d) < double.Epsilon;
+        return false;
+    }
+
+    public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo? culture)
+        => throw new NotSupportedException();
+}
+
diff --git a/src/AdvancedCalculator/Converters/WidthToPaneOpenConverter.cs b/src/AdvancedCalculator/Converters/WidthToPaneOpenConverter.cs
new file mode 100644
index 0000000..13ec666
--- /dev/null
+++ b/src/AdvancedCalculator/Converters/WidthToPaneOpenConverter.cs
@@ -0,0 +1,29 @@
+using System;
+using System.Globalization;
+using Avalonia.Data.Converters;
+
+namespace AdvancedCalculator.Converters;
+
+public class WidthToPaneOpenConverter : IValueConverter
+{
+    public static readonly WidthToPaneOpenConverter Instance = new();
+
+    public object? Convert(object? value, Type targetType, object? parameter, CultureInfo? culture)
+    {
+        if (value is double width)
+        {
+            double threshold = 640;
+            if (parameter is double p)
+                threshold = p;
+            else if (parameter is string s && double.TryParse(s, NumberStyles.Number, CultureInfo.InvariantCulture, out var parsed))
+                threshold = parsed;
+
+            return width >= threshold;
+        }
+        return true;
+    }
+
+    public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo? culture)
+        => throw new NotSupportedException();
+}
+
diff --git a/src/AdvancedCalculator/Converters/WidthToSplitViewModeConverter.cs b/src/AdvancedCalculator/Converters/WidthToSplitViewModeConverter.cs
new file mode 100644
index 0000000..efb420a
--- /dev/null
+++ b/src/AdvancedCalculator/Converters/WidthToSplitViewModeConverter.cs
@@ -0,0 +1,30 @@
+using System;
+using System.Globalization;
+using Avalonia.Controls;
+using Avalonia.Data.Converters;
+
+namespace AdvancedCalculator.Converters;
+
+public class WidthToSplitViewModeConverter : IValueConverter
+{
+    public static readonly WidthToSplitViewModeConverter Instance = new();
+
+    public object? Convert(object? value, Type targetType, object? parameter, CultureInfo? culture)
+    {
+        if (value is double width)
+        {
+            double threshold = 640;
+            if (parameter is double p)
+                threshold = p;
+            else if (parameter is string s && double.TryParse(s, NumberStyles.Number, CultureInfo.InvariantCulture, out var parsed))
+                threshold = parsed;
+
+            return width < threshold ? SplitViewDisplayMode.Overlay : SplitViewDisplayMode.Inline;
+        }
+        return SplitViewDisplayMode.Inline;
+    }
+
+    public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo? culture)
+        => throw new NotSupportedException();
+}
+
diff --git a/src/AdvancedCalculator/Styles/Scroll.axaml b/src/AdvancedCalculator/Styles/Scroll.axaml
index ea9284d..4f1e590 100644
--- a/src/AdvancedCalculator/Styles/Scroll.axaml
+++ b/src/AdvancedCalculator/Styles/Scroll.axaml
@@ -1,15 +1,11 @@
-<ResourceDictionary xmlns="https://github.com/avaloniaui"
-                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+<Styles xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
   <!-- Shared scrolling defaults -->
   <Style Selector="ListBox">
     <Setter Property="ScrollViewer.VerticalScrollBarVisibility" Value="Auto"/>
     <Setter Property="ScrollViewer.HorizontalScrollBarVisibility" Value="Disabled"/>
   </Style>
 
-  <Style Selector="ScrollViewer">
-    <Setter Property="CanScrollHorizontally" Value="False"/>
-  </Style>
-
   <!-- Thin-ish scrollbars by default; platform overrides will adjust -->
   <Style Selector="ScrollBar:vertical">
     <Setter Property="Width" Value="10"/>
@@ -17,5 +13,4 @@
   <Style Selector="ScrollBar:horizontal">
     <Setter Property="Height" Value="10"/>
   </Style>
-</ResourceDictionary>
-
+</Styles>
diff --git a/src/AdvancedCalculator/Styles/Typography.axaml b/src/AdvancedCalculator/Styles/Typography.axaml
index eb80272..e6d5f62 100644
--- a/src/AdvancedCalculator/Styles/Typography.axaml
+++ b/src/AdvancedCalculator/Styles/Typography.axaml
@@ -1,18 +1,20 @@
-<ResourceDictionary xmlns="https://github.com/avaloniaui"
-                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
-  <!-- Shared typography resources -->
-  <x:Double x:Key="FontSizeSmall">12</x:Double>
-  <x:Double x:Key="FontSizeBase">14</x:Double>
-  <x:Double x:Key="FontSizeLarge">16</x:Double>
-  <x:Double x:Key="FontSizeXL">20</x:Double>
+<Styles xmlns="https://github.com/avaloniaui"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+  <Styles.Resources>
+    <!-- Shared typography resources -->
+    <x:Double x:Key="FontSizeSmall">12</x:Double>
+    <x:Double x:Key="FontSizeBase">14</x:Double>
+    <x:Double x:Key="FontSizeLarge">16</x:Double>
+    <x:Double x:Key="FontSizeXL">20</x:Double>
 
-  <x:Double x:Key="IconSizeS">18</x:Double>
-  <x:Double x:Key="IconSizeM">22</x:Double>
-  <x:Double x:Key="IconSizeL">26</x:Double>
+    <x:Double x:Key="IconSizeS">18</x:Double>
+    <x:Double x:Key="IconSizeM">22</x:Double>
+    <x:Double x:Key="IconSizeL">26</x:Double>
 
-  <x:Double x:Key="LineHeightTight">1.1</x:Double>
-  <x:Double x:Key="LineHeightBase">1.25</x:Double>
-  <x:Double x:Key="LineHeightRelaxed">1.4</x:Double>
+    <x:Double x:Key="LineHeightTight">1.1</x:Double>
+    <x:Double x:Key="LineHeightBase">1.25</x:Double>
+    <x:Double x:Key="LineHeightRelaxed">1.4</x:Double>
+  </Styles.Resources>
 
   <!-- Defaults for text -->
   <Style Selector="TextBlock">
@@ -26,5 +28,4 @@
     <Setter Property="TextElement.FontSize" Value="{DynamicResource FontSizeSmall}"/>
     <Setter Property="Opacity" Value="0.85"/>
   </Style>
-</ResourceDictionary>
-
+</Styles>
diff --git a/src/AdvancedCalculator/Views/MainView.axaml b/src/AdvancedCalculator/Views/MainView.axaml
index d5fc5e7..981363e 100644
--- a/src/AdvancedCalculator/Views/MainView.axaml
+++ b/src/AdvancedCalculator/Views/MainView.axaml
@@ -11,34 +11,16 @@
   <UserControl.Resources>
     <conv:BoolToGridLengthConverter x:Key="BoolToGridLengthConverter" />
     <conv:WidthToBooleanConverter x:Key="WidthToBooleanConverter" />
+    <conv:IsZeroConverter x:Key="IsZeroConverter" />
+    <conv:WidthToSplitViewModeConverter x:Key="WidthToSplitViewModeConverter" />
+    <conv:WidthToPaneOpenConverter x:Key="WidthToPaneOpenConverter" />
   </UserControl.Resources>
   <!-- Replace columns with a responsive SplitView -->
   <SplitView x:Name="RootSplit"
              OpenPaneLength="320"
-             CompactPaneLength="0">
-    <!-- Responsive behavior: set DisplayMode and IsPaneOpen based on width -->
-    <SplitView.Styles>
-      <Style Selector="SplitView#RootSplit">
-        <Style.Triggers>
-          <!-- Narrow: Overlay mode, pane closed by default -->
-          <DataTrigger Value="True"
-                       Binding="{Binding $parent[Window].Bounds.Width,
-                                         Converter={StaticResource WidthToBooleanConverter},
-                                         ConverterParameter=640}">
-            <Setter Property="DisplayMode" Value="Overlay" />
-            <Setter Property="IsPaneOpen" Value="False" />
-          </DataTrigger>
-          <!-- Wide: Inline mode, pane open -->
-          <DataTrigger Value="False"
-                       Binding="{Binding $parent[Window].Bounds.Width,
-                                         Converter={StaticResource WidthToBooleanConverter},
-                                         ConverterParameter=640}">
-            <Setter Property="DisplayMode" Value="Inline" />
-            <Setter Property="IsPaneOpen" Value="True" />
-          </DataTrigger>
-        </Style.Triggers>
-      </Style>
-    </SplitView.Styles>
+             CompactPaneLength="0"
+             DisplayMode="{Binding $parent[Window].Bounds.Width, Converter={StaticResource WidthToSplitViewModeConverter}, ConverterParameter=640}"
+             IsPaneOpen="{Binding $parent[Window].Bounds.Width, Converter={StaticResource WidthToPaneOpenConverter}, ConverterParameter=640}">
 
     <!-- Left pane: Variables + Functions -->
     <SplitView.Pane>
@@ -50,11 +32,11 @@
 
         <!-- Variables list with empty-state hint overlay -->
         <Grid Grid.Row="0">
-          <ListBox ItemsSource="{Binding Variables}" SelectedIndex="-1" HorizontalContentAlignment="Stretch"
+          <ListBox ItemsSource="{Binding Variables}" SelectedIndex="-1"
                    AutomationProperties.Name="Variables list">
             <ListBox.ItemTemplate>
               <DataTemplate x:DataType="m:VariableItem">
-                <Button Command="{Binding DataContext.InsertVariableCommand, RelativeSource={RelativeSource AncestorType=UserControl}}"
+                <Button Command="{Binding $parent[UserControl].DataContext.InsertVariableCommand}"
                         CommandParameter="{Binding VariableName}"
                         Background="Transparent" BorderThickness="0" Padding="8" MinHeight="44"
                         AutomationProperties.Name="Insert variable">
@@ -72,29 +54,19 @@
             </ListBox.ItemTemplate>
           </ListBox>
           <TextBlock Text="No variables yet. Define with: x = 5"
-                     IsVisible="False"
+                     IsVisible="{Binding Variables.Count, Converter={StaticResource IsZeroConverter}}"
                      IsHitTestVisible="False"
                      Opacity="0.6"
-                     HorizontalAlignment="Center" VerticalAlignment="Center">
-            <TextBlock.Styles>
-              <Style Selector="TextBlock">
-                <Style.Triggers>
-                  <DataTrigger Binding="{Binding Variables.Count}" Value="0">
-                    <Setter Property="IsVisible" Value="True" />
-                  </DataTrigger>
-                </Style.Triggers>
-              </Style>
-            </TextBlock.Styles>
-          </TextBlock>
+                     HorizontalAlignment="Center" VerticalAlignment="Center" />
         </Grid>
 
         <!-- Function definitions -->
-        <ListBox Grid.Row="1" BorderThickness="0" HorizontalContentAlignment="Stretch"
+        <ListBox Grid.Row="1" BorderThickness="0"
                  ItemsSource="{x:Static m:FunctionDefinitionItem.DefinedFunctions}"
                  AutomationProperties.Name="Functions list">
           <ListBox.ItemTemplate>
             <DataTemplate x:DataType="m:FunctionDefinitionItem">
-              <Button Command="{Binding DataContext.InsertFunctionCommand, RelativeSource={RelativeSource AncestorType=UserControl}}"
+              <Button Command="{Binding $parent[UserControl].DataContext.InsertFunctionCommand}"
                       CommandParameter="{Binding FunctionName}"
                       Background="Transparent" BorderThickness="0" Padding="8" MinHeight="44"
                       AutomationProperties.Name="Insert function">
@@ -143,24 +115,14 @@
             </ListBox.ItemTemplate>
           </ListBox>
           <TextBlock Text="No history yet. Enter an expression and Evaluate."
-                     IsVisible="False"
+                     IsVisible="{Binding History.Count, Converter={StaticResource IsZeroConverter}}"
                      IsHitTestVisible="False"
                      Opacity="0.6"
-                     HorizontalAlignment="Center" VerticalAlignment="Center">
-            <TextBlock.Styles>
-              <Style Selector="TextBlock">
-                <Style.Triggers>
-                  <DataTrigger Binding="{Binding History.Count}" Value="0">
-                    <Setter Property="IsVisible" Value="True" />
-                  </DataTrigger>
-                </Style.Triggers>
-              </Style>
-            </TextBlock.Styles>
-          </TextBlock>
+                     HorizontalAlignment="Center" VerticalAlignment="Center" />
         </Grid>
 
         <!-- Input Row -->
-        <Grid Grid.Row="1" ColumnDefinitions="Auto,Auto,*,Auto" Margin="4" ColumnSpacing="6">
+        <Grid Grid.Row="1" ColumnDefinitions="Auto,Auto,*,Auto" Margin="4">
           <!-- Pane toggle: visible on narrow only -->
           <ToggleButton Margin="0,0,6,0"
                         IsVisible="{Binding $parent[Window].Bounds.Width,