/// Tries to find a unit that would match a CSS length
/// @access private
/// @param {Number} $number - number
/// @param {String}   $unit - potential unit
/// @return {Number} length (0 if cast failed)
@function _sc-length($number, $unit) {
  $strings: 'px' 'cm' 'mm' '%' 'ch' 'pc' 'in' 'em' 'rem' 'pt' 'pc' 'ex' 'vw' 'vh' 'vmin' 'vmax';
  $units:   1px  1cm  1mm  1%  1ch  1pc  1in  1em  1rem  1pt  1pc  1ex  1vw  1vh  1vmin  1vmax;
  $index: index($strings, $unit);

  @if not $index {
    @warn "Unknown unit `#{inspect($unit)}`.";
    @return 0;
  }

  @return $number * nth($units, $index);
}