title: Dynamic height for a child div when the position is relative
body: <p>It seems a duplicated question but unfortunately I didn't find answers for this simple scenario when the <code>Position</code> is <code>Relative</code>.</p>
  
  <p>I have a parent div with two child divs:</p>
  
  <pre><code>&lt;div id="content"&gt;
      &lt;div id="content_rdivider"&gt;&amp;nbsp;&lt;/div&gt;
      &lt;div id="content_right"&gt;&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>where both parent and child divs have a <code>position:relative;</code></p>
  
  <p>A Jsfiddle example is <a href="http://jsfiddle.net/9c4MK/21/" rel="nofollow noreferrer">HERE</a></p>
  
  <p>So my question is almost like <a href="https://stackoverflow.com/questions/3049783/how-to-make-a-floated-div-100-height-of-its-parent">THIS</a> question but the position is not absolute here.</p>
  
  <p>How do I make the height of <code>content_rdivider</code> div the same as the height of the parent div?</p>