title: CSS background color not showing up?
body: <p>I made two classes in which one is main and other one is a child div. In main div I give width of 100% background color:red and in child div I give width 100% and background blue and margin top 100px. But in browser red color is not showing up. If I use float in main div then color is appearing in browser but the main class already have width 100% so we are not supposed to give float element in it.</p>
  
  <pre><code>&lt;style&gt;
  
  .main {width:100%; background-color:#FF0000}
  
  .child { width:100%; margin-top:100px; background:#0000FF}
  
  &lt;/style&gt;
  
  &lt;/head&gt;
  
  &lt;body&gt;
  
  &lt;div class="main"&gt;   
      &lt;div class="child"&gt;asfda&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>