The hex color #3f3bb7 is a dark color. The web-safe version is Hex
#3333CC. A complementary color is
#C0C448. The grayscale version is
#666666. A 20% lighter version of the original color is
#726EEA, and Hex
#0C0884 is the 20% darker color. If the color is saturated by 10%, you get
#3B37BF. If the color is desaturated by 10%, the color
#433FAF is obtained.