The hex color #646e7f is a dark color. The web-safe version is Hex
#666666. A complementary color is
#9B9180. The grayscale version is
#707070. A 20% lighter version of the original color is
#97A1B2, and Hex
#313B4C is the 20% darker color. If the color is saturated by 10%, you get
#636E80. If the color is desaturated by 10%, the color
#656E7E is obtained.