The hinges, I believe, were mistakenly pre-screwed by the manufacturer into the top of the front panel and not the rear panel.  This means some of the black inner lining ( as it overlaps the top of the panel) is visible when the seat lid is closed. The panel that had the hinges pre-fixed does not have the interior lining showing on the top, it is white like the rest of the unit. I couldn’t simply swap panels as, if I did, there would be screw holes visible from the original hinge fitting. Not good.