@function rem($pixel, $basis: 16) {
  $negative: false;
  @if ($pixel < 0) {
    $negative: true;
    $pixel: calc($pixel * -1);
  }

  $rem: calc($pixel / $basis);

  @if ($negative) {
    $rem: calc($rem * -1);
  }

  @return $rem + 0rem;
}