2.1.6 [W3C-CSS3-Color] Section 4.2.4, HSL color values


The specification states:

 HSL colors are encoding as a triple (hue, saturation, lightness). Hue is 
 represented as an angle of the color circle (i.e. the rainbow represented in a 
 circle). This angle is so typically measured in degrees that the unit is implicit 
 in CSS; syntactically, only a <number> is given.

Quirks Mode, IE7 Mode, and IE8 Mode (All Versions)

HSL color values are not supported.