The hex color #3f45a3 is a dark color. The web-safe version is Hex
#333399. A complementary color is
#C0BA5C. The grayscale version is
#626262. A 20% lighter version of the original color is
#7278D6, and Hex
#0C1270 is the 20% darker color. If the color is saturated by 10%, you get
#3B42A9. If the color is desaturated by 10%, the color
#43489D is obtained.