The hex color #31919c is a dark color. The web-safe version is Hex
#339999. A complementary color is
#CE6E63. The grayscale version is
#757575. A 20% lighter version of the original color is
#64C4CF, and Hex
#005E69 is the 20% darker color. If the color is saturated by 10%, you get
#2A94A0. If the color is desaturated by 10%, the color
#388E98 is obtained.