The hex color #c71d0f is a dark color. The web-safe version is Hex
#CC3300. A complementary color is
#38E2F0. The grayscale version is
#515151. A 20% lighter version of the original color is
#FA5042, and Hex
#940000 is the 20% darker color. If the color is saturated by 10%, you get
#D31808. If the color is desaturated by 10%, the color
#BB2216 is obtained.