The hex color #66fc3c is a light color. The web-safe version is Hex
#66FF33. A complementary color is
#9903C3. The grayscale version is
#8A8A8A. A 20% lighter version of the original color is
#99FF6F, and Hex
#33C909 is the 20% darker color. If the color is saturated by 10%, you get
#62FF34. If the color is desaturated by 10%, the color
#6AF144 is obtained.