title: display flex - keeping last element in full width
body: <p>I am trying to keep my 3d element with full width of the <code>flex</code> container. but not getting the reuslt. any one suggest me the right way for <code>ie11</code> here?</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>.parent{
    border:1px solid red;
    display:flex;
    justify-content:space-between;
    padding:0 40px;
  }
  
  .child{
    flex:0 0 30%;
    border:1px dashed green;
  }
  
  .child.last{
  /* not working */
    width:100%;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="parent"&gt;
    &lt;div class="child"&gt;one&lt;/div&gt;
    &lt;div class="child"&gt;two&lt;/div&gt;
    &lt;div class="child last"&gt;three&lt;/div&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>