The hex color #31788c is a dark color. The web-safe version is Hex
#336699. A complementary color is
#CE8773. The grayscale version is
#676767. A 20% lighter version of the original color is
#64ABBF, and Hex
#004559 is the 20% darker color. If the color is saturated by 10%, you get
#2C7A90. If the color is desaturated by 10%, the color
#367688 is obtained.