title: force the child div width to match the parent div width
body: <p>I have this following HTML elements.</p>
  
  <pre><code>&lt;div id="theparent"&gt;
      &lt;div class="thechild"&gt;
          &lt;div class="anotherchild"&gt;&lt;/div&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>and the CSS for those elements.</p>
  
  <pre><code>#theparent{width: 90%;}
  .thechild{width: 100%; padding: 10px;}
  .anotherchild{}
  </code></pre>
  
  <p>Now what I want is that the <code>.anotherchild</code> div width must be equal or leveled to the width of the <code>.theparent</code> div while keeping the padding of <code>.thechild</code> div, how to do that? any suggestions, recommendations and ideas is greatly appreciated.</p>