The hex color #51d4e7 is a light color. The web-safe version is Hex
#66CCFF. A complementary color is
#AE2B18. The grayscale version is
#AFAFAF. A 20% lighter version of the original color is
#84FFFF, and Hex
#1EA1B4 is the 20% darker color. If the color is saturated by 10%, you get
#48D8ED. If the color is desaturated by 10%, the color
#5AD0E1 is obtained.