title: CSS Select every 4th child not working
body: <p>The nth-child selector nth-child(4n) should normally select every fourth child matching.</p>
  
  <p>I have an example which matches every 3rd child, and I don't know why. </p>
  
  <p>Could you help me with this?</p>
  
  <pre><code>.line_4:nth-child(4n){
     background: #ff0000;
  }
  </code></pre>
  
  <p><a href="http://jsfiddle.net/YPRB9/33/" rel="nofollow">http://jsfiddle.net/YPRB9/33/</a></p>
  
  <p><div class="snippet" data-lang="js" data-hide="true" data-console="true" data-babel="false">
  <div class="snippet-code snippet-currently-hidden">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>.line_4:nth-child(4n) {
    background: #ff0000;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="mod_article first last block" id="article-591"&gt;
    &lt;h1 class="ce_headline first"&gt; Kategorieübersicht&lt;/h1&gt;
    &lt;div class="ce_text line_4 block"&gt;
      &lt;h3&gt;hydraulische Handpumpen&lt;/h3&gt;
    &lt;/div&gt;
    &lt;div class="ce_text line_4 block"&gt;
      &lt;h3&gt;elektr.Hydraulikpumpen&lt;/h3&gt;
    &lt;/div&gt;
    &lt;div class="ce_text line_4 block"&gt;
      &lt;h3&gt;Handhebelventile &amp;amp; Steuerventile&lt;/h3&gt;
    &lt;/div&gt;
    &lt;div class="ce_text line_4 block"&gt;
      &lt;h3&gt;Hydraulikschläuche&lt;/h3&gt;
    &lt;/div&gt;
    &lt;div class="ce_text line_4 block"&gt;
      &lt;h3&gt;Hydraulikkupplungen&lt;/h3&gt;
    &lt;/div&gt;
    &lt;div class="ce_text line_4 block"&gt;
      &lt;h3&gt;Hydraulikverschraubungen&lt;/h3&gt;
    &lt;/div&gt;
    &lt;div class="ce_text line_4 block"&gt;
      &lt;h3&gt;Kardanringe und Lagerböcke&lt;/h3&gt;
    &lt;/div&gt;
    &lt;div class="ce_text line_4 last block"&gt;
      &lt;h3&gt;Hydraulikventile&lt;/h3&gt;
    &lt;/div&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>