title: Javascript - change top style from "ul" as child from a div parent
body: <p>I want to change the top value from css using javascript but it doesn't work.</p>
  
  <p>I have the following code:</p>
  
  <p>HTML:</p>
  
  <pre><code>&lt;button onclick="Down()"&gt;Move Down&lt;/button&gt;
  &lt;div class="test"&gt;
      &lt;ul&gt;
          &lt;li&gt;Line one&lt;/li&gt;
          &lt;li&gt;Line two&lt;/li&gt;
          &lt;li&gt;Line three&lt;/li&gt;
      &lt;/ul&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>CSS:</p>
  
  <pre><code>.test {
      color:red;
      height: 200px;
      width: 200px;
  }
  .test ul{
      position: relative;
      top:50px;
  }
  </code></pre>
  
  <p>Javascript:</p>
  
  <pre><code>function Down() {
      var class_obj = document.getElementsByClassName("test");
      var ul_obj = class_obj.getElementsByTagName("ul");
      ul_obj.style.top = parseInt(ul_obj.style.top, 10) + 10 + "px"; 
  }
  </code></pre>
  
  <p><a href="http://jsfiddle.net/fUmJR/" rel="nofollow">http://jsfiddle.net/fUmJR/</a></p>
  
  <p>What am I missing?</p>