Schwim Dandy is giving good advice here. If it were me, I’d take down the shelf, spackle and sand the wall a bit with one of those foam sanding blocks, use painter’s masking tape to make a frame around the area on the wall, paint the area inside the frame of tape some darker color, then put the shelf back up. The shelf will look nice on the rectangle of paint and everything will look clean.
Schwim Dandy is giving good advice here. If it were me, I’d take down the shelf, spackle and sand the wall a bit with one of those foam sanding blocks, use painter’s masking tape to make a frame around the area on the wall, paint the area inside the frame of tape some darker color, then put the shelf back up. The shelf will look nice on the rectangle of paint and everything will look clean.