The hex color #3b51a4 is a dark color. The web-safe version is Hex
#336699. A complementary color is
#C4AE5B. The grayscale version is
#656565. A 20% lighter version of the original color is
#6E84D7, and Hex
#081E71 is the 20% darker color. If the color is saturated by 10%, you get
#374FAA. If the color is desaturated by 10%, the color
#3F539E is obtained.