The hex color #51636c is a dark color. The web-safe version is Hex
#666666. A complementary color is
#AE9C93. The grayscale version is
#606060. A 20% lighter version of the original color is
#84969F, and Hex
#1E3039 is the 20% darker color. If the color is saturated by 10%, you get
#50636D. If the color is desaturated by 10%, the color
#53636B is obtained.