The hex color #291ddc is a dark color. The web-safe version is Hex
#3333CC. A complementary color is
#D6E223. The grayscale version is
#616161. A 20% lighter version of the original color is
#5C50FF, and Hex
#0000A9 is the 20% darker color. If the color is saturated by 10%, you get
#2316E8. If the color is desaturated by 10%, the color
#2F24D0 is obtained.