styles.css

/* 
HSL stands for hue, saturation, and lightness.
HSL color values are specified with: 
hsl(hue, saturation, lightness).
Hue is a degree on the color wheel from 0 to 360. 0 is red, 120 is green, 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; 0% is black, 100% is white.
*/

* {
  margin: 0;
}

.box {
  width: 100px;
  height: 100px;
  margin: 20px;
  border: 2px solid red;
}

.box-1 {
  background: hsl(0, 100%, 50%);
}

.box-2 {
  background: hsl(120, 100%, 50%);
}

.box-3 {
  background: hsl(120, 50%, 50%);
}

.box-4 {
  background: hsl(120, 100%, 0%);
}

.box-5 {
  background: hsl(120, 100%, 100%);
}