The hex color #66537c is a dark color. The web-safe version is Hex
#666666. A complementary color is
#99AC83. The grayscale version is
#676767. A 20% lighter version of the original color is
#9986AF, and Hex
#332049 is the 20% darker color. If the color is saturated by 10%, you get
#66517E. If the color is desaturated by 10%, the color
#66557A is obtained.