The hex color #81f40e is a light color. The web-safe version is Hex
#99FF00. A complementary color is
#7E0BF1. The grayscale version is
#818181. A 20% lighter version of the original color is
#B4FF41, and Hex
#4EC100 is the 20% darker color. If the color is saturated by 10%, you get
#81FF03. If the color is desaturated by 10%, the color
#81E91A is obtained.