Try this style instead, it modifies the template itself. In there you can change everything you need to transparent: <Style TargetType=”{x:Type TabItem}”> <Setter Property=”Template”> <Setter.Value> <ControlTemplate TargetType=”{x:Type TabItem}”> <Grid> <Border Name=”Border” Margin=”0,0,0,0″ Background=”Transparent” BorderBrush=”Black” BorderThickness=”1,1,1,1″ CornerRadius=”5″> <ContentPresenter x:Name=”ContentSite” VerticalAlignment=”Center” HorizontalAlignment=”Center” ContentSource=”Header” Margin=”12,2,12,2″ RecognizesAccessKey=”True”> <ContentPresenter.LayoutTransform> <RotateTransform Angle=”270″ /> </ContentPresenter.LayoutTransform> </ContentPresenter> </Border> </Grid> <ControlTemplate.Triggers> <Trigger Property=”IsSelected” Value=”True”> … Read more