wpf Button 动态改变效果

<Button  x:Name="LearnMore"  Grid.Row="6"  HorizontalAlignment="Left" VerticalAlignment="Top" Click="go_webSite" >
                        <Button.Template>
                            <ControlTemplate TargetType="Button">
                                <Border Background="{TemplateBinding Button.Background}"  Cursor="Hand" CornerRadius="21" Height="42" Width="160">
                                    <StackPanel Orientation="Horizontal" HorizontalAlignment="Center">
                                        <TextBlock  Height="25" VerticalAlignment="Center" Margin="0,4,0,0" Width="73" Foreground="#FFFFFF" FontSize="18"   TextAlignment="Center"  >了解更多</TextBlock>
                                        <Image Width="14" Margin="8,2,0,0" Height="12" Source="/Imgs/arrow.png" />
                                    </StackPanel>
                                </Border>
                                <ControlTemplate.Triggers>
                                    <Trigger  Property="Button.IsMouseOver"  Value="True">
                                        <Setter Property="Button.Background" Value="#0096D6" />
                                    </Trigger>
                                    <Trigger  Property="Button.IsMouseOver"  Value="false">
                                        <Setter Property="Button.Background" Value="#177BBF" />
                                    </Trigger>
                                    <Trigger  Property="Button.IsPressed"  Value="true">
                                        <Setter Property="Button.Background" Value="#2285C9" />
                                    </Trigger>
                                </ControlTemplate.Triggers>
                            </ControlTemplate>
                        </Button.Template>
                    </Button>