maui-linux/Xamarin.Forms.Platform.WPF/Themes/FormsNavigationPage.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                    xmlns:controls="clr-namespace:Xamarin.Forms.Platform.WPF.Controls">

    <Style TargetType="controls:FormsNavigationPage">
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="HorizontalAlignment" Value="Stretch"/>
        <Setter Property="VerticalAlignment" Value="Stretch"/>
        <Setter Property="FocusVisualStyle" Value="{x:Null}"/>
        <Setter Property="TitleBarBackgroundColor" Value="{DynamicResource DefaultTitleBarBackgroundColor}"/>
        <Setter Property="TitleBarTextColor" Value="{DynamicResource DefaultTitleBarTextColor}"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="controls:FormsNavigationPage">
                    <controls:FormsTransitioningContentControl x:Name="PART_Navigation_Content" Transition="Normal"
                        ContentLoader="{TemplateBinding ContentLoader}" Source="{TemplateBinding CurrentPage}" />

                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</ResourceDictionary>