WPF border and textbox issue .NET 3.5 - wpf

Question

I have a rounded border around a textbox. When displaying it, the horizontal top and bottom lines of the textbox are shown despite setting "BorderThickness" property to 0 and "BorderBrush" to transparent. How can I do borders for textbox to be not shown?
Below the code:
<Border Grid.Row="0" Grid.Column="0"
BorderBrush="DarkBlue"
BorderThickness="0.8"
CornerRadius="5"
Margin="5,10,3,10"
Height="Auto" Width="Auto"
Background="AliceBlue"
HorizontalAlignment="Left">
<TextBox x:Name="txtSearch"
Width="250"
Style="{StaticResource WatermarkedTextBox}"
VerticalAlignment="Center"
HorizontalAlignment="Left"
BorderBrush="Transparent"
BorderThickness="0"
Margin="1"/>
</Border>
Any ideas why textbox borders are being displayed?
ATTEMPT #1:
I have found that the culprit is the style attached, that is the static resource WatermarkedTextBox which is as follows:
<Style x:Key="WatermarkedTextBox" TargetType="TextBox">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="TextBox">
<Grid>
<TextBox Text="{Binding Text, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}, UpdateSourceTrigger=PropertyChanged}" />
<TextBlock HorizontalAlignment="Left" VerticalAlignment="Center"
Text="{TemplateBinding Tag}"
Margin="5,0,5,0"
Foreground="#FF808080"
FontStyle="Italic"
IsHitTestVisible="False"
x:Name="UserMessage"
Visibility="Hidden"/>
</Grid>
<ControlTemplate.Triggers>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="Text" Value=""/>
<Condition Property="IsKeyboardFocusWithin" Value="False"/>
</MultiTrigger.Conditions>
<Setter Property="Visibility" TargetName="UserMessage" Value="Visible"/>
</MultiTrigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
So how can I solve this?

Answer 1

The culprit was the border of the textbox set in the style "WatermarkedTextbox" so setting BorderThickness property to 0 is working now:
<Style x:Key="WatermarkedTextBox" TargetType="TextBox">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="TextBox">
<Grid>
<TextBox BorderThickness="0"
Text="{Binding Text, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}, UpdateSourceTrigger=PropertyChanged}" />
<TextBlock HorizontalAlignment="Left" VerticalAlignment="Center"
Text="{TemplateBinding Tag}"
Margin="5,0,5,0"
Foreground="#FF808080"
FontStyle="Italic"
IsHitTestVisible="False"
x:Name="UserMessage"
Visibility="Hidden"/>
</Grid>
<ControlTemplate.Triggers>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="Text" Value=""/>
<Condition Property="IsKeyboardFocusWithin" Value="False"/>
</MultiTrigger.Conditions>
<Setter Property="Visibility" TargetName="UserMessage" Value="Visible"/>
</MultiTrigger>
</ControlTemplate.Triggers>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>