How to set the background for all usercontrols in app resources (white background: using dark mode)

gistfile1.txt

<!--https://stackoverflow.com/questions/5183801/black-background-for-xaml-editor-->

<Application
    ...
    xmlns:componentModel="clr-namespace:System.ComponentModel;assembly=PresentationFramework">
    ...
    <Application.Resources>
        ...
        <Style TargetType="Control">
            <Style.Triggers>
                <Trigger Property="componentModel:DesignerProperties.IsInDesignMode"
                         Value="True">
                    <Setter Property="Background" Value="White" />
                </Trigger>
            </Style.Triggers>
        </Style>