The hex color #f81c29 is a dark color. The web-safe version is Hex
#FF3333. A complementary color is
#07E3D6. The grayscale version is
#6A6A6A. A 20% lighter version of the original color is
#FF4F5C, and Hex
#C50000 is the 20% darker color. If the color is saturated by 10%, you get
#FF1423. If the color is desaturated by 10%, the color
#EA242F is obtained.