//************************************************************************//
// Helper function for str-to-num fn.
// Source: http://sassmeister.com/gist/9647408
//************************************************************************//
@function _convert-units($number, $unit) {
  $strings: 'px' 'cm' 'mm' '%' 'ch' 'pica' 'in' 'em' 'rem' 'pt' 'pc' 'ex' 'vw' 'vh' 'vmin' 'vmax', 'deg', 'rad', 'grad', 'turn';
  $units:   1px  1cm  1mm  1%  1ch  1pica  1in  1em  1rem  1pt  1pc  1ex  1vw  1vh  1vmin  1vmax,  1deg,  1rad,  1grad, 1turn;
  $index: index($strings, $unit);

  @if not $index {
    @warn "Unknown unit `#{$unit}`.";
    @return false;
  }
  @return $number * nth($units, $index);
}