The hex color #51a155 is a light color. The web-safe version is Hex
#669966. A complementary color is
#AE5EAA. The grayscale version is
#6D6D6D. A 20% lighter version of the original color is
#84D488, and Hex
#1E6E22 is the 20% darker color. If the color is saturated by 10%, you get
#4EA653. If the color is desaturated by 10%, the color
#549C57 is obtained.