如果我设置自己的表单，MenuItem 周围的黑色区域

我正在尝试实现我自己的菜单样式，但找不到需要覆盖的内容。为了进行比较，我创建了一个没有菜单的单独项目，并且弹出窗口正确显示。

和代码：

    <Canvas>
    <Button x:Name="button" Content="show" Canvas.Left="10" Canvas.Top="10" Click="button_Click"/>
    <Popup x:Name="popup" Placement="Center" HorizontalOffset="10" VerticalOffset="10" AllowsTransparency="True" PopupAnimation="Slide">
        <Popup.Resources>
            <Style x:Key="opac"><!-- просто анимация, ничего интересного -->

            </Style>
        </Popup.Resources>
        <StackPanel Opacity="0" Style="{StaticResource opac}">
            <Path Margin="10,0,0,0" Fill="#e5323232" Data="M 0 6 L 6 0 L 12 6 Z"/>
            <Border CornerRadius="3,3,0,0" HorizontalAlignment="Center" VerticalAlignment="Top" Padding="10,7" BorderThickness="0" Background="#e5323232">
                <StackPanel>
                    <TextBlock Foreground="White">
            Очередное ничего не значащее, чтобы забить пространство
                    </TextBlock>
                </StackPanel>
            </Border>
        </StackPanel>
    </Popup>
    <Button x:Name="button1" Content="hide" Canvas.Left="110" Canvas.Top="10" Click="button1_Click"/>
</Canvas>

但是当我尝试在菜单中执行相同的操作时，会添加黑色区域，但我无法摆脱。

        <Style TargetType="{x:Type MenuItem}">
        <Setter Property="Foreground" Value="White"/>
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type MenuItem}">
                    <Border x:Name="templateRoot" SnapsToDevicePixels="True">
                        <Grid Margin="-1">
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition/>
                                <ColumnDefinition/>
                            </Grid.ColumnDefinitions>
                            <ContentPresenter x:Name="Icon" Content="{TemplateBinding Icon}" ContentSource="Icon" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                            <Path x:Name="GlyphPanel" Data="F1M10,1.2L4.7,9.1 4.5,9.1 0,5.2 1.3,3.5 4.3,6.1 8.3,0 10,1.2z" Fill="#e5323232"/>
                            <ContentPresenter ContentTemplate="{TemplateBinding HeaderTemplate}" Content="{TemplateBinding Header}" Grid.Column="1" ContentStringFormat="{TemplateBinding HeaderStringFormat}" ContentSource="Header" Margin="{TemplateBinding Padding}" RecognizesAccessKey="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                            <Popup Focusable="False" IsOpen="{Binding IsSubmenuOpen, RelativeSource={RelativeSource TemplatedParent}}" Placement="Right">
                                <StackPanel>
                                    <Path Margin="10,0,0,0" Fill="#e5323232" Data="M 0 6 L 6 0 L 12 6 Z"/>
                                    <Border CornerRadius="3,3,0,0" HorizontalAlignment="Center" VerticalAlignment="Top" Padding="10,7" BorderThickness="0" Background="#e5323232">
                                        <StackPanel>
                                            <ItemsPresenter KeyboardNavigation.DirectionalNavigation="Cycle" Grid.IsSharedSizeScope="True" SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}" KeyboardNavigation.TabNavigation="Cycle"/>
                                        </StackPanel>
                                    </Border>
                                </StackPanel>
                            </Popup>
                        </Grid>
                    </Border>

                    <ControlTemplate.Triggers>
                        <Trigger Property="IsChecked" Value="True">
                            <Setter Property="Visibility" TargetName="GlyphPanel" Value="Visible"/>
                            <Setter Property="Visibility" TargetName="Icon" Value="Collapsed"/>
                        </Trigger>
                    </ControlTemplate.Triggers>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
        <Setter Property="Background" Value="#e5323232"/>
    </Style>