An over-engineered way of creating lighter and darker colours based on an original

After reading this article about how a darker version of a colour would hue shift and re-saturate, as would the lighter version hue shift and de-saturate. I decided that would be a cool thing to program.

The SASS function accepts a colour and returns a map with the original, darkened and lightened versions, with the correct hue shift and a logged scale lighten and saturation, as not all colours are equal.

The hue shift is the most interesting as it depends on where you are on the colour spectrum as to which way you should shift.