message: Remove timer background (win)
diff: <Style TargetType="UserControl" x:Key="Timer" BasedOn="{StaticResource {x:Type Control}}">
  <Setter Property="Height" Value="{StaticResource TimerHeight}" />
  - <Setter Property="Background" Value="{StaticResource ViewBackground}" />
  <Style.Resources>
  <Style TargetType="TextBlock" BasedOn="{StaticResource TimerTextBlockBase}" />
  