title: jQuery and pseudo-elements
body: <p>I tried to dynamically change the position of an element which is defined in CSS with <code>:after</code>. 
  Using this:</p>
  
  <pre><code>$(function(){
      $('div::after').css({'top':'20px'})
  })
  </code></pre>
  
  <p>But it doesn't work. Are there any ways to change the position?</p>