title: What are the "no-content style elements"?
body: <p><a href="http://css-tricks.com/15135-simple-styles-for-horizontal-rules/" rel="nofollow">This cool article</a> briefly discusses no-content style elements. Particularities include that they don't have closing brackets, and <code>:before:</code> and <code>:after</code> cannot be used on them. Examples include <code>hr</code> and <code>br</code>.</p>
  
  <p>Where can I find an exhaustive list of such elements?</p>