Убрать Margin у TabItem

<LinearGradientBrush x:Key="LightBrush" StartPoint="0,0" EndPoint="0,1">
      <GradientBrush.GradientStops>
        <GradientStopCollection>
          <GradientStop Color="#FFFFFF" Offset="0.0"/>
          <GradientStop Color="#EEEEEE" Offset="1.0"/>
        </GradientStopCollection>
      </GradientBrush.GradientStops>
    </LinearGradientBrush>
 
    <SolidColorBrush x:Key="SolidBorderBrush" Color="#888888" />
 
    <SolidColorBrush x:Key="WindowBackgroundBrush" Color="#FFFFFF" />
 
    <SolidColorBrush x:Key="DisabledBackgroundBrush" Color="#EEEEEE" />
 
    <SolidColorBrush x:Key="DisabledBorderBrush" Color="#AAAAAA" />
 
    <SolidColorBrush x:Key="DisabledForegroundBrush" Color="#888888" />
    
    <Style TargetType="{x:Type TabItem}">
      <Setter Property="Template">
        <Setter.Value>
          <ControlTemplate TargetType="{x:Type TabItem}">
            <Grid>
              <Border
                Name="Border"
                Margin="0"
                Background="{StaticResource LightBrush}"
                BorderBrush="{StaticResource SolidBorderBrush}"
                BorderThickness="1,1,1,0"
                CornerRadius="0,0,0,0" >
                <ContentPresenter x:Name="ContentSite"
                  VerticalAlignment="Center"
                  HorizontalAlignment="Center"
                  ContentSource="Header"
                  Margin="12,2,12,2"
                  RecognizesAccessKey="True"/>
              </Border>
            </Grid>
            <ControlTemplate.Triggers>
              <Trigger Property="IsSelected" Value="True">
                <Setter Property="Panel.ZIndex" Value="100" />
                <Setter TargetName="Border" Property="Background" Value="{StaticResource WindowBackgroundBrush}" />
                <Setter TargetName="Border" Property="BorderThickness" Value="1,1,1,0" />
              </Trigger>
              <Trigger Property="IsEnabled" Value="False">
                <Setter TargetName="Border" Property="Background" Value="{StaticResource DisabledBackgroundBrush}" />
                <Setter TargetName="Border" Property="BorderBrush" Value="{StaticResource DisabledBorderBrush}" />
                <Setter Property="Foreground" Value="{StaticResource DisabledForegroundBrush}" />
              </Trigger>
            </ControlTemplate.Triggers>
          </ControlTemplate>
        </Setter.Value>
      </Setter>
    </Style>
.......
 <TabControl>
      <TabItem Header="Tab1"></TabItem>
      <TabItem Header="Tab2"></TabItem>
      <TabItem Header="Tab3"></TabItem>
    </TabControl>