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

  @if type-of($number) != "number" {
    @warn "`#{$number} is not a number`";
    @return false;
  }

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