I know how to change the background color of a scrollbar:
<ScrollBar Height="27" Margin="36,96,12,0" Name="scrollBar1" Background="Red"></ScrollBar>
here is the picture with my red background:

How could I do the same thing with ScrollViewer? I have a grid inside my ScrollViewer and if I change the properties of ScrollViewer it seem to change the properties of the content inside my grid.
<ScrollViewer>
<Grid Name="Parent">
<Grid.RowDefinitions>
<RowDefinition Height="Auto" />
<RowDefinition Height="Auto" />
....
....
... etc
that produces:

with the content of my grid named Parent on the left. How could I place a red background on this ScrollViewer?