<DataGridTextColumn.ElementStyle>
<Style TargetType="TextBlock" >
<Setter Property="Foreground" Value="Black" />
<Setter Property="Background" Value="Yellow" />
</Style>
</DataGridTextColumn.ElementStyle>
<DataGridTextColumn.EditingElementStyle>
<Style TargetType="TextBox" >
<Setter Property="Foreground" Value="Black" />
<Setter Property="Background" Value="Yellow" />
</Style>
</DataGridTextColumn.EditingElementStyle>