_pems.scss

/* See http://mrdanadams.com/2012/pixel-ems-css-conversion-sass-mixin/ */

/* Default font size in pixels if not overridden. */
$baseFontSize: 16;

/* Convert PX units to EMs.
Ex: margin-right: pem(16);
*/
@function pem($pxval, $base: $baseFontSize) {
  @return #{$pxval / $base}em;
}

/* Used to convert PX to EMs for multiple properties or values or both.
$base is an optional measurement that allows making measurements relative to the parent font size rather than the current. Also accepts a list of lists (instead a list of values) for properties that accept multiple lists of values. Only numbers of converted; everything else is passed through.

Examples:

@include scale(line-height, 30)
@include scale(line-height, 30, 16)
@include scale(width height, 125);
@include scale(padding, 0 25, 16);
@include scale(text-shadow, (#0d6e28 1 1) (#777 0 0 2), 16);
@include scale(box-shadow, (inset 0 0 0 1 #2a9022) (inset 0 0 3 #459966), 16);
*/
@mixin scale($props, $sizes, $base: $baseFontSize) {
    $values: ();
    $sublists: false;
    @each $s in $sizes {
        /* unwrap lists for values that have multiple list of values such as text-shadow */
        @if type-of($s) == list {
            $sublists: true;
            $vv: ();
            @each $ss in $s {
                $vv: append($vv, if(type-of($ss) == number, #{$ss / $base}em, $ss));
            }
            $values: append($values, join((), $vv));
        } @else {
            $values: append($values, if(type-of($s) == number, #{$s / $base}em, $s));
        }
    }
    $value: join((), $values, if($sublists, comma, space));
    @each $prop in $props { #{$prop}: $value }
}