title: How do get visual topmost element - jQuery
body: <p>Is there a neat way to get the topmost element using jQuery?</p>
  
  <p>I don't mean with respect to DOM hierarchy. i.e. <code>.closest()</code> is not what I need.</p>
  
  <p>I mean, with respect to <code>z-index</code> and obviously it should be currently <code>:visible</code></p>
  
  <p>I was starting out to write a custom selector, but thought it would be better to see if there are better approaches.</p>