In the form’s on current trigger, simply check the Active / inactive field and set the background property of the detail section accordingly. You can do it in a Macro or VBA code. I put a VBA code example below.
Private Sub Form_Current()
If Me![active] Then ‘ <active] is a bound field to recordsource
Me.Section(0).BackColor = 255 ‘set detail section to red when active
Me.Section(0).BackColor = -2147483633 ‘set detail section to standard gray when not active