改变颜色按钮与角圆

I found this code: XAML:

我发现了这个代码:XAML:

<Button Content="Click Me!" Margin="209,135,263.4,140.8" Background="{x:Null}" BorderBrush="{x:Null}" Click="Button_Click_1">
        <Button.Template>
            <ControlTemplate TargetType="{x:Type Button}">
                <Border x:Name="bdr_main" CornerRadius="3" Margin="0" BorderThickness="1" BorderBrush="Black" Background="LightGray">
                    <ContentPresenter VerticalAlignment="Center" HorizontalAlignment="Center" Margin="8,6,8,6" ContentSource="Content" />
                </Border>
                <ControlTemplate.Triggers>
                    <Trigger Property="IsMouseOver" Value="True">
                        <Setter TargetName="bdr_main" Property="Background" Value="LightGreen"/>
                    </Trigger>
                    <Trigger Property="IsPressed" Value="True">
                        <Setter TargetName="bdr_main" Property="Background" Value="Red"/>
                    </Trigger>
                </ControlTemplate.Triggers>
            </ControlTemplate>
        </Button.Template>
    </Button>
<Bu