The hex color #3d91d0 is a dark color. The web-safe version is Hex
#3399CC. A complementary color is
#C26E2F. The grayscale version is
#8A8A8A. A 20% lighter version of the original color is
#70C4FF, and Hex
#0A5E9D is the 20% darker color. If the color is saturated by 10%, you get
#3592D7. If the color is desaturated by 10%, the color
#4590C9 is obtained.