The hex color #31b51f is a dark color. The web-safe version is Hex
#33CC33. A complementary color is
#CE4AE0. The grayscale version is
#575757. A 20% lighter version of the original color is
#64E852, and Hex
#008200 is the 20% darker color. If the color is saturated by 10%, you get
#2DBE19. If the color is desaturated by 10%, the color
#35AC25 is obtained.