title: z-index is not working inside table
body: <p>Why <strong>z-index</strong> is not working inside table?
  I have a table with 4 column that one column is positioned outside of table, so that it seem as tabs, but I cannot hidden right side of tabs under table.</p>
  
  <p>Please see this code snippet:</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>div {
    position: relative;
    z-index: 5;
    width: 70%;
    margin: auto;
    height: 500px;
    background-color: red;
  }
  
  table {
    border: none;
    border-spacing: 0 11px;
    width: 100%;
    table-layout: fixed;
  }
  
  td.tab {
    background-color: white;
    padding: 15px;
    width: 20%;
    position: absolute;
    z-index: -15;
    right: 90%;
  }
  
  td.plan {
    padding: 15px;
    width: 33.3%;
    text-align: center;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="bottom"&gt;
    &lt;table&gt;
      &lt;tbody&gt;
        &lt;tr&gt;
          &lt;td class="tab"&gt;test&lt;/td&gt;
          &lt;td class="plan"&gt;test&lt;/td&gt;
          &lt;td class="plan"&gt;test&lt;/td&gt;
          &lt;td class="plan"&gt;test&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td class="tab"&gt;test&lt;/td&gt;
          &lt;td class="plan"&gt;test&lt;/td&gt;
          &lt;td class="plan"&gt;test&lt;/td&gt;
          &lt;td class="plan"&gt;test&lt;/td&gt;
        &lt;/tr&gt;
        &lt;tr&gt;
          &lt;td class="tab"&gt;test&lt;/td&gt;
          &lt;td class="plan"&gt;test&lt;/td&gt;
          &lt;td class="plan"&gt;test&lt;/td&gt;
          &lt;td class="plan"&gt;test&lt;/td&gt;
        &lt;/tr&gt;
      &lt;/tbody&gt;
    &lt;/table&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p><a href="https://jsfiddle.net/ghanbari/bxzomqct/" rel="nofollow noreferrer">fiddle code</a></p>
  
  <hr>
  
  <p><strong>EDIT</strong>: I no want tabs, I will add our plans to site.
  I update <a href="https://jsfiddle.net/ghanbari/bxzomqct/9/" rel="nofollow noreferrer">fiddle</a>, I want remove this shadow on right side of tabs.</p>
  
  <p><a href="https://jsfiddle.net/ghanbari/bxzomqct/9/" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/lof78.jpg" alt="enter image description here"></a></p>