HSL Color Values In HTML, a color can be specified using hue, saturation, and lightness (HSL) in the form: hsl(hue, saturation, lightness) Hue is a degree on the color wheel from 0 to 360. 0 is red, 120 is green, and 240 is blue. Saturation is a percentage value. 0% means a shade of gray, and 100% is the full color. Lightness is also a percentage value. 0% is black, and 100% is white. Experiment by mixing the HSL values below: