jellyfin/MediaBrowser.UI/Resources/MainWindowResources.xaml

<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">

    <!--Themes should override this to style the window-->
    <Style TargetType="Window" x:Key="MainWindow" BasedOn="{StaticResource BaseWindow}">
    </Style>

    <!--Themes may want to override this to adjust the backdrop container style-->
    <Style TargetType="Grid" x:Key="BackdropGrid">
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="Opacity" Value=".15"/>
    </Style>

    <!--Themes may want to override this to adjust the backdrop image style-->
    <Style TargetType="Image" x:Key="BackdropImage">
        <Setter Property="Stretch" Value="UniformToFill"/>
    </Style>

    <Style TargetType="Grid" x:Key="DragBar">
        <Setter Property="Background" Value="Transparent"/>
        <Setter Property="Height" Value="50"/>
        <Setter Property="VerticalAlignment" Value="Top"/>
        <Setter Property="Panel.ZIndex" Value="1"/>
    </Style>
    <Style TargetType="UserControl" x:Key="WindowCommands">
        <Setter Property="Margin" Value="0 10 0 0"/>
        <Setter Property="HorizontalAlignment" Value="Right"/>
        <Setter Property="VerticalAlignment" Value="Top"/>
        <Setter Property="Panel.ZIndex" Value="2"/>
        <Setter Property="Visibility" Value="Collapsed" />
        <Style.Triggers>
            <DataTrigger Binding="{Binding Path=MainWindow.IsMouseIdle}" Value="false">
                <Setter Property="Visibility" Value="Visible" />
            </DataTrigger>
        </Style.Triggers>
    </Style>

    <!--Themes should override this to layout window content-->
    <ControlTemplate x:Key="PageContentTemplate">
        <Frame x:Name="PageFrame"></Frame>
    </ControlTemplate>

</ResourceDictionary>