//************************************************************************//
// 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);
}