to_lower_case($string) Convert a string to lower case,

ie_hex_str($color) Converts a color into the format understood by IE filters.

str_index($string, $substring) Returns the index of the first occurrence of $substring in $string

simple_selectors($selector) Returns the simple

change_color($color, [$red], [$green], [$blue], [$hue], [$saturation], [$lightness], [$alpha]) Changes one or more properties

hsl($hue, $saturation, $lightness) Creates a Color from hue, saturation, and lightness values

opacity($color) Returns the alpha component (opacity) of a color. This is 1 unless otherwise specified.

nth($list, $n) Gets the nth item in a list. Note that unlike some languages, the first item

comparable($number1, $number2) Returns whether two numbers can added, subtracted, or compared.

floor($number) Rounds a number down to the previous whole number.