The hex color #51637e is a dark color. The web-safe version is Hex
#666666. A complementary color is
#AE9C81. The grayscale version is
#666666. A 20% lighter version of the original color is
#8496B1, and Hex
#1E304B is the 20% darker color. If the color is saturated by 10%, you get
#4F6380. If the color is desaturated by 10%, the color
#53637C is obtained.