Why does the :empty pseudo-selector affect elements that don't have a closing tag?

Gotta simulate an <hr> :/

CSS: *:empty { border:green 3px solid; }

  1. Image tag: <img src="http://lorempixel.com/400/200/sports/2 " alt="">

  2. Input: <input type="text">

  3. Horizontal Rule: <hr>


  4. Per @davidelrizzo comment, unclosed <p> : It doesn't get affected

  5. Here's a short screencast by Russ Weakley in Sitepoint that explains the :empty pseudo-class better:

    Understanding the :empty Pseudo-Class (Screencast)

Created by Ricardo Zea