The hex color #668dcf is a light color. The web-safe version is Hex
#6699CC. A complementary color is
#997230. The grayscale version is
#969696. A 20% lighter version of the original color is
#99C0FF, and Hex
#335A9C is the 20% darker color. If the color is saturated by 10%, you get
#618CD5. If the color is desaturated by 10%, the color
#6B8EC9 is obtained.