u/Helpful_Supermarket7

I had an unfortunate moment when I dropped my book and a corner landed in some not very clean water. It dried out fine but there's a line at the edge of where the water reached. Is there any way to remove the stain without damaging the cover ? I tried gently rubbing the stain with a very lightly wet microfiber cloth but I don't think it's doing much. Any tip would be very appreciated! Have a great day