title: How to add placeholder <input type="datetime-local"> field?
body: <p>I've been trying to add placeholder in input type='datetime-local' field but it doesn't work at all. Use css for solving the issue but still unable to do it :(</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>   input[type="datetime-local"]:before{
      content: 'Selecteer Datum';
      color: #000;
      text-align: center;
      width:100%;
  }
  input[type="datetime-local"]:active:before, input[type="datetime-local"]:hover:before, input[type="datetime-local"]:visited:before,  input[type="datetime-local"]:focus:before{
      content: '';
      width: 100%;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;form action="" method="post"&gt;
      &lt;div class="datetime"&gt;
          &lt;input type="datetime-local"  &gt;
      &lt;/div&gt;
  &lt;/form&gt;
      
      </code></pre>
  </div>
  </div>
  </p>