The hex color #3f90cf is a dark color. The web-safe version is Hex
#3399CC. A complementary color is
#C06F30. The grayscale version is
#8A8A8A. A 20% lighter version of the original color is
#72C3FF, and Hex
#0C5D9C is the 20% darker color. If the color is saturated by 10%, you get
#3891D6. If the color is desaturated by 10%, the color
#478FC8 is obtained.