Removing shadow from button WPF

I've created style for button in my WPF app:

<Style x:Key="buttonStyle" TargetType="Button">
    <Setter Property="Border.BorderBrush" Value="Black" />
    <Setter Property="Border.BorderThickness" Value="1" />
    <Setter Property="Border.Background" Value="White" />
    <Setter Property="Height" Value="25" />
    <Setter Property="Width" Value="100" />
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Button">
                <Border
                    Width="{TemplateBinding Width}"
                    Height="{TemplateBinding Height}"
                    Background="{TemplateBinding Background}"
                    BorderBrush="{TemplateBinding BorderBrush}"
                    BorderThickness="{TemplateBinding BorderThickness}">
                    <ContentPresenter
                        HorizontalAlignment="Center"
                        VerticalAlignment="Center"
                        Content="{TemplateBinding Content}"
                        ContentTemplate="{TemplateBinding ContentTemplate}" />
                </Border>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsMouseOver" Value="True">
                        <Setter Property="Background" Value="Red" />
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

Then I'm putting this style to Button control:

<Button Style="{StaticResource buttonStyle}" Grid.Row="1" Grid.Column="1" Content="Press"/>

When I'm running my app, I see grey shadow under and right of the button. Futhermore when I look in Visual Studio view I don't see shadow. How can I delete this effect? Anyone an idea or an completly other approach?