title: Sass deprecation warning on mixin that converts px to rem
body: <p>I have a mixin that converts px to rem. I've recently been getting the following deprecation warning when I try build. Can anyone suggest a fix.</p>
  
  <p>DEPRECATION WARNING on line 135 of 
  source/css/partials/global/mixins.scss:
  The result of <code>0px == 0</code> will be <code>false</code> in future releases of Sass.
  Unitless numbers will no longer be equal to the same numbers with units.</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>@function parseInt($n) {
      @return $n / ($n * 0 + 1);
  }
  
  @mixin rem($property, $values) {
      $px: ();
      $rem: ();
      @each $value in $values {
          @if $value==0 or $value==auto {
              $px: append($px, $value);
              $rem: append($rem, $value);
          }
          @else {
              $unit: unit($value);
              $val: parseInt($value);
              @if $unit=="px" {
                  $px: append($px, $value);
                  $rem: append($rem, ($val / 16 + rem));
              }
              @if $unit=="rem" {
                  $px: append($px, ($val * 16 + px));
                  $rem: append($rem, $value);
              }
          }
      }
      @if $px==$rem {
          #{$property}: $px;
      }
      @else {
          #{$property}: $px;
          #{$property}: $rem;
      }
  }</code></pre>
  </div>
  </div>
  </p>