The hex color #c31d3b is a dark color. The web-safe version is Hex
#CC3333. A complementary color is
#3CE2C4. The grayscale version is
#5E5E5E. A 20% lighter version of the original color is
#F6506E, and Hex
#900008 is the 20% darker color. If the color is saturated by 10%, you get
#CD1637. If the color is desaturated by 10%, the color
#B9243F is obtained.