Avalonia/samples/ControlCatalog/Pages/NavigationPage/NavigationPageAppearancePage.xaml

<UserControl xmlns="https://github.com/avaloniaui"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             x:Class="ControlCatalog.Pages.NavigationPageAppearancePage">
  <DockPanel>
    <ScrollViewer DockPanel.Dock="Right" Width="260">
      <StackPanel Margin="12" Spacing="8">
        <TextBlock Text="Configuration" FontWeight="SemiBold" FontSize="16"
                   Foreground="{DynamicResource SystemControlHighlightAccentBrush}" />
        <TextBlock Text="Visibility" FontWeight="SemiBold" FontSize="13" />

        <CheckBox x:Name="HasNavBarCheck"
                  Content="Has Navigation Bar"
                  IsChecked="True"
                  IsCheckedChanged="OnHasNavBarChanged" />
        <CheckBox x:Name="HasShadowCheck"
                  Content="Has Shadow"
                  IsCheckedChanged="OnHasShadowChanged" />

        <Separator />

        <TextBlock Text="Bar Background" FontWeight="SemiBold" FontSize="14" />
        <ComboBox x:Name="BarBgCombo"
                  SelectedIndex="0"
                  HorizontalAlignment="Stretch"
                  SelectionChanged="OnBarBgChanged">
          <ComboBoxItem Content="Default" />
          <ComboBoxItem Content="DodgerBlue" />
          <ComboBoxItem Content="DarkSlateGray" />
          <ComboBoxItem Content="Indigo" />
          <ComboBoxItem Content="Crimson" />
          <ComboBoxItem Content="Transparent" />
          <ComboBoxItem Content="Semi-transparent dark" />
        </ComboBox>

        <Separator />

        <TextBlock Text="Bar Foreground" FontWeight="SemiBold" FontSize="14" />
        <ComboBox x:Name="BarFgCombo"
                  SelectedIndex="0"
                  HorizontalAlignment="Stretch"
                  SelectionChanged="OnBarFgChanged">
          <ComboBoxItem Content="Default" />
          <ComboBoxItem Content="White" />
          <ComboBoxItem Content="Black" />
          <ComboBoxItem Content="Yellow" />
        </ComboBox>

        <Separator />

        <TextBlock Text="Bar Height" FontWeight="SemiBold" FontSize="14" />
        <DockPanel>
          <TextBlock x:Name="BarHeightLabel"
                     DockPanel.Dock="Right"
                     Text="48"
                     FontSize="12"
                     Opacity="0.6"
                     VerticalAlignment="Center"
                     Width="28"
                     TextAlignment="Right" />
          <Slider x:Name="BarHeightSlider"
                  Minimum="30"
                  Maximum="80"
                  Value="48"
                  TickFrequency="1"
                  IsSnapToTickEnabled="True"
                  ValueChanged="OnBarHeightChanged" />
        </DockPanel>

        <Separator />

        <TextBlock Text="Per-Page Bar Height" FontWeight="SemiBold" FontSize="14" />
        <ComboBox x:Name="PerPageBarHeightCombo"
                  SelectedIndex="0"
                  HorizontalAlignment="Stretch"
                  SelectionChanged="OnPerPageBarHeightChanged">
          <ComboBoxItem Content="Inherit global" />
          <ComboBoxItem Content="Small (32px)" />
          <ComboBoxItem Content="Large (72px)" />
        </ComboBox>
        <TextBlock Text="Overrides bar height on the current page only. Push a detail page to see it change per page."
                   FontSize="11"
                   Opacity="0.6"
                   TextWrapping="Wrap" />

        <Separator />

        <TextBlock Text="Title Style" FontWeight="SemiBold" FontSize="14" />
        <ComboBox x:Name="TitleStyleCombo"
                  SelectedIndex="0"
                  HorizontalAlignment="Stretch"
                  SelectionChanged="OnTitleStyleChanged">
          <ComboBoxItem Content="Default (string)" />
          <ComboBoxItem Content="Bold + Large" />
          <ComboBoxItem Content="Title + Subtitle" />
        </ComboBox>

        <Separator />

        <TextBlock Text="Bar Layout Behavior" FontWeight="SemiBold" FontSize="14" />
        <ComboBox x:Name="BarLayoutCombo"
                  SelectedIndex="0"
                  HorizontalAlignment="Stretch"
                  SelectionChanged="OnBarLayoutChanged">
          <ComboBoxItem Content="Inset (default)" />
          <ComboBoxItem Content="Overlay" />
        </ComboBox>
        <TextBlock Text="Overlay: content extends behind the bar. Combine with Transparent background to see it."
                   FontSize="11"
                   Opacity="0.6"
                   TextWrapping="Wrap" />

        <Separator />

        <TextBlock Text="Back Button Style" FontWeight="SemiBold" FontSize="14" />
        <ComboBox x:Name="BackButtonStyleCombo"
                  SelectedIndex="0"
                  HorizontalAlignment="Stretch"
                  SelectionChanged="OnBackButtonStyleChanged">
          <ComboBoxItem Content="Default icon" />
          <ComboBoxItem Content="Text: ← Back" />
          <ComboBoxItem Content="Text: Cancel" />
        </ComboBox>
        <TextBlock Text="Push a detail page to see the styled back button."
                   FontSize="11"
                   Opacity="0.6"
                   TextWrapping="Wrap" />

        <Separator />

        <Button Content="Push Page"
                HorizontalAlignment="Stretch"
                Click="OnPush" />
        <Button Content="Pop"
                HorizontalAlignment="Stretch"
                Click="OnPop" />
      </StackPanel>
    </ScrollViewer>

    <Border DockPanel.Dock="Right" Width="1" Background="{DynamicResource SystemControlForegroundBaseMediumLowBrush}" />

    <Border Margin="12"
            BorderBrush="{DynamicResource SystemControlForegroundBaseMediumLowBrush}"
            BorderThickness="1"
            CornerRadius="6"
            ClipToBounds="True">
      <NavigationPage x:Name="DemoNav" />
    </Border>
  </DockPanel>
</UserControl>