title: How to set margin in section?
body: <p>Cant understand how to set margin in wrapped element. For example i have</p>
  
  <pre><code>&lt;body&gt;
      &lt;section id="main"&gt;
          &lt;div id="video"&gt;
  
          &lt;/div&gt;
  
      &lt;/section&gt;
  &lt;/body&gt;
  
  
  section#main{
      width: 960px;
      margin: 7% auto 0;
      background: #000;
      opacity: 0.86;
      -webkit-border-radius: 5px;
      -moz-border-radius: 5px;
      border-radius: 5px; 
  }
  
  div#video{
      border: 1px solid red;
      width: 640px;
      height: 360px;
      margin: 10px;
  }
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/SwykO.png" alt="enter image description here"></p>
  
  <p>As you can see - margin only on left and right.</p>