The hex color #66fa9c is a light color. The web-safe version is Hex
#66FF99. A complementary color is
#990563. The grayscale version is
#A9A9A9. A 20% lighter version of the original color is
#99FFCF, and Hex
#33C769 is the 20% darker color. If the color is saturated by 10%, you get
#5FFF9B. If the color is desaturated by 10%, the color
#6DF29D is obtained.