The hex color #40e9ef is a light color. The web-safe version is Hex
#33FFFF. A complementary color is
#BF1610. The grayscale version is
#B3B3B3. A 20% lighter version of the original color is
#73FFFF, and Hex
#0DB6BC is the 20% darker color. If the color is saturated by 10%, you get
#35EEF5. If the color is desaturated by 10%, the color
#4BE4E9 is obtained.