How to Set style for DataGrid header in WPF

Question

I have a DataGrid like this:

Answer 1

To avoid the effect of the header collapsing simply correct your style in this way:

  <Setter Property="HorizontalAlignment" Value="Stretch" />
  <Setter Property="HorizontalContentAlignment" Value="Center" />

Answer 2

Adding the Style for DatagridColumnHeader of the Datagrid

<DataGrid Name="GatewayPortsDataGrid" Height="auto" Width="auto">
     <DataGrid.Resources>
            <Style BasedOn="{StaticResource {x:Type DataGridColumnHeader}}" TargetType="{x:Type DataGridColumnHeader}" >
            <Setter Property="Background" Value="White" />
            <Setter Property="Foreground" Value="Black" />                                   
            <Setter Property="BorderBrush" Value="Black"/>                                  
            <Setter Property="BorderThickness" Value="1 1 1 1"/>                               
            <Setter Property="Margin" Value="-1,-1,0,0" />
            <Setter Property="Height" Value="28" />                                                                    
            <Setter Property="Width" Value="auto"/>                                    
            <Setter Property="HorizontalContentAlignment" Value="Center"/>                                                                        
            </Style>
        </DataGrid.Resources>
</DataGrid>