title: after not appearing when hiding bg_img to img
body: <p>While using <code>@media queries</code>, I'm currently using <code>uk-hidden@m</code> for my <code>img {}</code> class and use my <code>bg_img {}</code>class with <code>uk-visible@m</code>.
  and this is what they look like: <br></p>
  <blockquote>
  <p>(bg_img uk-visible@m)</p>
  </blockquote>
  <pre><code>.bg-image {
     position: relative;
     height: ~px;
     width: ~px;
     box-shadow: 10px 11px 10px 1px rgba(0, 0, 0, 0.25);
     &amp;::after {
         position: absolute;
         content: '';
         bottom: -46px;
         left: 0;
         height: 46px;
         width: 80%
         background-color: #DCCA7E;
         z-index: -1;
     }
     @include breakpoint(small down) {
         height: 46.72;
     }
  }
  </code></pre>
  <blockquote>
  <p>(img uk-hidden@m)<br></p>
  </blockquote>
  <pre><code>img {
      &amp;::before {
         position: absolute;
         content: '';
         bottom: -46px;
         left: 0;
         height: 46px;
         width: 80%;
         background-color: #DCCA7E;
         z-index: -1;
     }
     @include breakpoint(medium down) {
         max-width: 140%;
     }
  }
  </code></pre>
  <p>my <code>&amp;::after</code> doesn´t show up at media screens before medium, size where <code>img{}</code> hides and <code>bg_img {}</code> appears. I want to understand WHY this happens, to prevent this in the future.</p>
  <p>Appreciate for those taking the time! :)</p>