#p1 {background-color: hsl(120, 100%, 50%);}   /* green */
#p2 {background-color: hsl(120, 100%, 75%);}   /* light green */
#p3 {background-color: hsl(120, 100%, 25%);}   /* dark green */
#p4 {background-color: hsl(120, 60%, 70%);}    /* pastel green */