<DataGrid.Resources>
    <SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="{StaticResource ThemeHighlightColor}"/>
    <SolidColorBrush x:Key="{x:Static SystemColors.InactiveSelectionHighlightBrushKey}" Color="{StaticResource ThemeHighlightColor}"/>
    <SolidColorBrush x:Key="{x:Static SystemColors.HighlightTextBrushKey}" Color="Black"/>
    <Style TargetType="{x:Type DataGridRow}">
        <Style.Triggers>
            <DataTrigger Binding="{Binding Path=active}" Value="False">
                <Setter Property="Foreground" Value="DarkOrchid"/>
                <Setter Property="FontWeight" Value="DemiBold"/>
            </DataTrigger>
            <DataTrigger Binding="{Binding Path=active}" Value="True">
                <Setter Property="Foreground" Value="Black"/>
                <Setter Property="FontWeight" Value="Normal"/>
            </DataTrigger>
        </Style.Triggers>
    </Style>
</DataGrid.Resources>

<MultiDataTrigger>
    <MultiDataTrigger.Conditions>
        <Condition Binding="{Binding Path=active}" Value="False"/>
        <Condition Binding="{Binding RelativeSource={RelativeSource Self}, Path=IsSelected}" Value="True"/>
    </MultiDataTrigger.Conditions>
    <MultiDataTrigger.Setters>
        <Setter Property="Foreground" Value="DarkOrchid"/>
        <Setter Property="FontWeight" Value="DemiBold"/>
    </MultiDataTrigger.Setters>
</MultiDataTrigger>

<Datagrid.Resouces>
  <Style TargetType="{x:Type TextBlock}" x:Key="Text">
    <Style.Triggers>
      <DataTrigger Binding="{Binding Path=active}" Value="False">
        <Setter Property="Foreground" Value="DarkOrchid"/>
        <Setter Property="FontWeight" Value="DemiBold"/>
      </DataTrigger>
      <DataTrigger Binding="{Binding Path=active}" Value="True">
        <Setter Property="Foreground" Value="Black"/>
        <Setter Property="FontWeight" Value="Normal"/>
      </DataTrigger>
    </Style.Triggers>
  </Style>
</Datagrid.Resouces>

<DataGridTextColumn Header="Name" Binding="{Binding FirstName}"
                    ElementStyle="{StaticResource Text}" />