How to add Placeholder or Watermark to a Password box in WPF

Question

I want to add placeholder to a password box i have achived that uptp some extent but the problem is that when i type the password, then the watermark text remains there like the image attached below:

<Border  Margin="0,0,0,10"  Grid.Column="0" Grid.Row="4" CornerRadius="7" BorderThickness="1" Grid.ColumnSpan="2" BorderBrush="Gray">
             <PasswordBox  Grid.Row="1" Margin="3,1,1,1" Grid.Column="1" x:Name="txtConfirmPassword"  BorderThickness="0,0,0,0"  VerticalContentAlignment="Center" HorizontalContentAlignment="Left"  Height="35" >
                 <PasswordBox.Style>
                     <Style xmlns:sys="clr-namespace:System;assembly=mscorlib" TargetType="{x:Type PasswordBox}">
                         <Style.Resources>
                             <VisualBrush x:Key="CueBannerBrush" AlignmentX="Left" Stretch="None">
                                 <VisualBrush.Visual>
                                     <Label Content="Confirm Password" Foreground="Gray" Padding="10"/>
                                 </VisualBrush.Visual>
                             </VisualBrush>
                         </Style.Resources>
                         <Style.Triggers>
                             <DataTrigger Binding="{Binding Password}" Value="{x:Null}">
                                 <Setter Property="Background" Value="{StaticResource CueBannerBrush}" />
                             </DataTrigger>
                             <Trigger Property="IsKeyboardFocused" Value="True">
                                 <Setter Property="Background" Value="White"/>
                             </Trigger>
                         </Style.Triggers>
                     </Style>
                 </PasswordBox.Style>
             </PasswordBox>
         </Border>