The hex color #66518c is a dark color. The web-safe version is Hex
#666699. A complementary color is
#99AE73. The grayscale version is
#6C6C6C. A 20% lighter version of the original color is
#9984BF, and Hex
#331E59 is the 20% darker color. If the color is saturated by 10%, you get
#654E8F. If the color is desaturated by 10%, the color
#675489 is obtained.