title: The easiest way to automatically open a popup?
body: <p>I wish to automatically open a popup when users enter my website.
  What is the easiest way to do this?</p>
  
  <ul>
  <li>The popup should be in a <code>div</code></li>
  <li>A close button should appear in order to close the popup</li>
  </ul>
  
  <p>I've tried a couple of solutions with jquery and CSS but sometimes the close button didn't close the popup and with other solutions sometimes the script just didn't work.</p>