title: How to make div below another div
body: <p>I want the <code>#blue</code> div below the <code>#green</code> div </p>
  
  <p>The <code>#blue</code> div has <code>margin-top : -10px; attribute</code></p>
  
  <pre><code> &lt;style&gt;
      #red{
          width: 400px;
  
          border: 1px solid red;
      }
      #green{
          width: 100%;
          height: 100px;
          background-color: green;
          border-bottom: 2px solid yellow;
          z-index: 2;
      }
      #blue{
          width: 100%;
          height: 100px;
          background-color: blue;
          border-top: 2px solid brown;
          margin-top: -10px;
          z-index: 1;
      }
      &lt;/style&gt;
  
  
  &lt;div id="red"&gt;
      &lt;div id="green"&gt;
      &lt;/div&gt;
      &lt;div id="blue"&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>