Update App.axaml

samples/ReactiveHistorySample.Base/App.axaml

@@ -1,8 +1,11 @@
 <Application x:Class="ReactiveHistorySample.App"
              xmlns="https://github.com/avaloniaui"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
-    <Application.Styles>
-        <StyleInclude Source="avares://Avalonia.Themes.Default/DefaultTheme.xaml"/>
-        <StyleInclude Source="avares://Avalonia.Themes.Default/Accents/BaseLight.xaml"/>
-    </Application.Styles>
+  <Application.Styles>
+    <FluentTheme Mode="Light" />
+    <Style Selector="Button">
+      <Setter Property="HorizontalAlignment" Value="Stretch" />
+      <Setter Property="HorizontalContentAlignment" Value="Center" />
+    </Style>
+  </Application.Styles>
 </Application>