>>1886120I think I see your problem.
Selected background with color-tolerance 12.
Note how red (unselected) extends outside the figure.
That's a dark halo which the eye interprets as a drop-shadow. So the figure seems in FRONT of the background.
I removed the halo, then applied 0.5 px Gaussian blur to boundary between black outline and gray background, visually fusing them.
Look better?