chore: minor modify.

Author: NaBian

src/Shared/HandyControlDemo_Shared/UserControl/Controls/TransitioningContentControlDemo.xaml

@@ -2,13 +2,14 @@
              xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
              xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
              xmlns:hc="https://handyorg.github.io/handycontrol"
-             Background="{DynamicResource RegionBrush}">
+             Background="{DynamicResource RegionBrush}"
+             MinWidth="320">
     <Grid>
         <Grid.RowDefinitions>
             <RowDefinition Height="Auto"/>
             <RowDefinition/>
         </Grid.RowDefinitions>
-        <ToggleButton Margin="0,32,0,0" IsChecked="True" Name="ButtonVisibilitySwitch" Style="{StaticResource ToggleButtonSwitch}"/>
+        <ToggleButton HorizontalAlignment="Center" Margin="0,32,0,0" IsChecked="True" Name="ButtonVisibilitySwitch" Style="{StaticResource ToggleButtonSwitch}"/>
         <hc:ScrollViewer IsInertiaEnabled="True" Grid.Row="1">
             <hc:UniformSpacingPanel Visibility="{Binding IsChecked,ElementName=ButtonVisibilitySwitch,Converter={StaticResource Boolean2VisibilityConverter}}" MaxWidth="720" Margin="32" Spacing="32" ChildWrapping="Wrap">
                 <hc:TransitioningContentControl>