This is an example of CSS3's hsl() colour support. The cssSandpaper library allows browsers that don't natively support it, like IE, join the party. It also illustrates how one can use the mneumonic "Young Guys Can Be Messy Rascals".

Red: 0°
Yellow: 60°
Green: 120°
Cyan: 180°
Blue: 240°
Magenta: 300°
HSL