The hex color #3f587f is a dark color. The web-safe version is Hex
#336666. A complementary color is
#C0A780. The grayscale version is
#5D5D5D. A 20% lighter version of the original color is
#728BB2, and Hex
#0C254C is the 20% darker color. If the color is saturated by 10%, you get
#3C5882. If the color is desaturated by 10%, the color
#42587C is obtained.