The hex color #b4fe3f is a light color. The web-safe version is Hex
#CCFF33. A complementary color is
#4B01C0. The grayscale version is
#A6A6A6. A 20% lighter version of the original color is
#E7FF72, and Hex
#81CB0C is the 20% darker color. If the color is saturated by 10%, you get
#B5FF35. If the color is desaturated by 10%, the color
#B3F549 is obtained.