The hex color #51a7d6 is a light color. The web-safe version is Hex
#6699CC. A complementary color is
#AE5829. The grayscale version is
#9A9A9A. A 20% lighter version of the original color is
#84DAFF, and Hex
#1E74A3 is the 20% darker color. If the color is saturated by 10%, you get
#4AA8DC. If the color is desaturated by 10%, the color
#58A6D0 is obtained.