如何删除网格中行之间的水平线？

Question

我在网格中有两行，并且有一条白线将行分隔开。如何将其删除？

这是我编写的代码。

<Window x:Class="Test.MainWindow"   
    <Grid ShowGridLines="False">
        <Grid.RowDefinitions>
            <RowDefinition Height="40"></RowDefinition>
            <RowDefinition Height="*"></RowDefinition>
        </Grid.RowDefinitions>

        <!--First Row-->
        <Grid Grid.Row="0" >
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="*"></ColumnDefinition>
                <ColumnDefinition Width="*"></ColumnDefinition>
            </Grid.ColumnDefinitions>
            <TextBlock Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="2"/>
        </Grid>

        <!-- Second Row -->
        <Grid Grid.Row="1" >
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="200"/>
                <ColumnDefinition Width="*"/>
            </Grid.ColumnDefinitions>

            <StackPanel  Orientation="Vertical" Grid.Column="0" Grid.Row="2" Background="#003049">
                <Button Content = "" Width= "auto" Height = "30">
                </Button>
            </StackPanel>
        </Grid>
    </Grid>
</Window>

<Window x:Class="Test.MainWindow" <Grid ShowGridLines="False"> <Grid.RowDefinitions> <RowDefinition Height="40"></RowDefinition> <RowDefinition Height="*"></RowDefinition> </Grid.RowDefinitions> <!--First Row--> <Grid Grid.Row="0" > <Grid.ColumnDefinitions> <ColumnDefinition Width="*"></ColumnDefinition> <ColumnDefinition Width="*"></ColumnDefinition> </Grid.ColumnDefinitions> <TextBlock Grid.Row="0" Grid.Column="0" Grid.ColumnSpan="2"/> </Grid> <!-- Second Row --> <Grid Grid.Row="1" > <Grid.ColumnDefinitions> <ColumnDefinition Width="200"/> <ColumnDefinition Width="*"/> </Grid.ColumnDefinitions> <StackPanel Orientation="Vertical" Grid.Column="0" Grid.Row="2" Background="#003049"> <Button Content = "" Width= "auto" Height = "30"> </Button> </StackPanel> </Grid> </Grid> </Window>