The hex color #66befc is a light color. The web-safe version is Hex
#66CCFF. A complementary color is
#994103. The grayscale version is
#B5B5B5. A 20% lighter version of the original color is
#99F1FF, and Hex
#338BC9 is the 20% darker color. If the color is saturated by 10%, you get
#5EBFFF. If the color is desaturated by 10%, the color
#6EBDF5 is obtained.