The hex color #3e66d1 is a dark color. The web-safe version is Hex
#3366CC. A complementary color is
#C1992E. The grayscale version is
#7C7C7C. A 20% lighter version of the original color is
#7199FF, and Hex
#0B339E is the 20% darker color. If the color is saturated by 10%, you get
#3864D9. If the color is desaturated by 10%, the color
#4468C9 is obtained.