wpf datagrid cell background color doesnt fill completely

Question

The background color leaves tiny space between the cell & grid lines. How could I make it fill completely? I have tried tried padding/margin = 0.

Screenshot:

Any styling experts out there?

 <DataGrid ItemsSource="{Binding}" >
     <DataGrid.CellStyle>
        <Style TargetType="DataGridCell">
           <Setter Property="Background" Value="Red"/>
        </Style>
     </DataGrid.CellStyle>
  </DataGrid>


  Data = new Dictionary<int,string>();         
     for (int i = 0; i < 5; i++)
        Data.Add(i, "Text");
  DataContext = Data;

Answer 1

This one's easy. Set the BorderThickness to 0:

<DataGrid ItemsSource="{Binding}" >
    <DataGrid.CellStyle>
        <Style TargetType="DataGridCell">
            <Setter Property="Background" Value="Red"/>
            <Setter Property="BorderThickness" Value="0" />
        </Style>
    </DataGrid.CellStyle>
</DataGrid>

Next time you wanna find out why things look how they look, give Snoop a try. Check the controls and panels, and their properties (in this case, it could be either Margin, Padding or BorderThickness), to see what you have to tweak from XAML.