I can see that i need to style the DetailsViewRowControl, but looking at the visual tree, it seems that the VirtualizingCellsControl (the row) and the DetailsViewRowControl (the area surrounding the detail SfDataGrid) both belong to the same parent and there is no property to connect a particular DetailsViewRowControl to the corresponding VirtualizingCellsControl .
If I can get a reference to the corresponding VirtualizingCellsControl from a particular DetailsViewRowControl then I can bind to that row's style DetailsViewRowControl.Background="{Binding Path=Background, Element=<Corresponding VirtualizingCellsControl>}".
Cheers,
James.