The hex color #646e9f is a dark color. The web-safe version is Hex
#666699. A complementary color is
#9B9160. The grayscale version is
#7B7B7B. A 20% lighter version of the original color is
#97A1D2, and Hex
#313B6C is the 20% darker color. If the color is saturated by 10%, you get
#626DA3. If the color is desaturated by 10%, the color
#666F9B is obtained.