diff --git a/demo/Semi.Avalonia.Demo/Pages/SplitViewDemo.axaml b/demo/Semi.Avalonia.Demo/Pages/SplitViewDemo.axaml
index ce8424a..041fe0f 100644
--- a/demo/Semi.Avalonia.Demo/Pages/SplitViewDemo.axaml
+++ b/demo/Semi.Avalonia.Demo/Pages/SplitViewDemo.axaml
@@ -48,6 +48,7 @@
                         Grid.Row="2" 
                         Grid.Column="1" 
                         Name="PanelPlacementSelector"
+                        HorizontalAlignment="Stretch"
                         ItemsSource="{x:Static vm:SplitViewDemoViewModel.Placements}"
                         SelectedItem="{x:Static SplitViewPanePlacement.Left}"
                         />