The hex color #c81c1d is a dark color. The web-safe version is Hex
#CC3333. A complementary color is
#37E3E2. The grayscale version is
#565656. A 20% lighter version of the original color is
#FB4F50, and Hex
#950000 is the 20% darker color. If the color is saturated by 10%, you get
#D31617. If the color is desaturated by 10%, the color
#BD2223 is obtained.