This macro creates a colour using the given hue (h) angle in degrees, as well as the given saturation (s) and lightness (l) percentages.
(hsl: 120, 0.8, 0.5)produces a colour with 120 degree hue, 80% saturation and 50% lightness.
(hsl: 28, 1, 0.4)'s hproduces the number 28.
The HSL colour model is regarded as easier to work with than the RGB model used for HTML hexadecimal notation and the (rgb:) macro. Being able to set the hue with one number instead of three, for instance, lets you control the hue using a single variable, and alter it at will.
This macro takes the same range of numbers as the CSS
Giving saturation or lightness values higher than 1 or lower than 0 will cause an error. However,
you can give any kind of hue number to (hsl:), and it will automatically round it to fit the 0-359
degree range. This allows you to cycle through hues easily by providing a steadily increasing variable or
a counter, such as
(hsl: time / 100, 1, 0.5).