如何在ControlTemplate中用触发器覆盖通用样式？

<Style TargetType="Button">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="Button">
                <Grid>
                    <Border x:Name="border" Background="Gray" BorderBrush="Black" BorderThickness="1" CornerRadius="5">
                        <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center"/>
                    </Border>
                </Grid>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsMouseOver" Value="True">
                        <Setter TargetName="border" Property="Background" Value="LightGray"/>
                    </Trigger>
                    <Trigger Property="IsPressed" Value="True">
                        <Setter TargetName="border" Property="Background" Value="DarkGray"/>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>