<Grid>
  <Grid.RowDefinitions>
    <RowDefinition />
    <RowDefinition />
  </Grid.RowDefinitions>
  <Grid.Resources>
    <Style TargetType="{x:Type DataGrid}">
      <Setter Property="Background" Value="Aqua" />
      <Style.Triggers>
        <Trigger Property="IsFocused" Value="True">
          <Setter Property="Background" Value="LightSlateGray" />
        </Trigger>
        <Trigger Property="IsKeyboardFocusWithin" Value="True">
          <Setter Property="Background" Value="Red" />
        </Trigger>
      </Style.Triggers>
    </Style>
    <Style TargetType="{x:Type DataGridCell}">
      <Style.Triggers>
        <Trigger Property="IsFocused" Value="True">
          <Setter Property="Background" Value="Yellow" />
          <Setter Property="Foreground" Value="Black" />
        </Trigger>
      </Style.Triggers>
    </Style>
    <Style TargetType="{x:Type DataGridRow}">
      <Style.Triggers>
        <Trigger Property="IsFocused" Value="True">
          <Setter Property="Background" Value="Green" />
        </Trigger>
        <Trigger Property="IsKeyboardFocusWithin" Value="True">
	  <Setter Property="Background" Value="DarkMagenta" />
        </Trigger>
      </Style.Triggers>
    </Style>
  </Grid.Resources>
  <TextBox
    VerticalAlignment="Center"
    Margin="10" />
  <DataGrid
    Grid.Row="1"
    IsReadOnly="True"
    AutoGenerateColumns="False"
    ItemsSource="{Binding}">
    <DataGrid.Columns>
      <DataGridTextColumn
        Header="Text"
        Binding="{Binding}" />
    </DataGrid.Columns>
  </DataGrid>
</Grid>

public partial class MainWindow
{
  public MainWindow()
  {
    InitializeComponent();
    DataContext = Items;
  }

  public ObservableCollection<string> Items { get; }
    = new ObservableCollection<string>(new[] { "Foo", "Bar", "Zot" });
}