The hex color #3f40b0 is a dark color. The web-safe version is Hex
#333399. A complementary color is
#C0BF4F. The grayscale version is
#656565. A 20% lighter version of the original color is
#7273E3, and Hex
#0C0D7D is the 20% darker color. If the color is saturated by 10%, you get
#3B3CB8. If the color is desaturated by 10%, the color
#4344A9 is obtained.