title: margin-right is not working with my HTML. How can I center my content?
body: <p>Recently, I am learning <strong>Responsive Design</strong>.&nbsp;&nbsp;But I've got some trouble in centering my content when the screen gets big.</p>
  
  <p>Here is the problem:</p>
  
  <pre><code>@media screen and (min-width: 950px) {
      body {
          margin: 10%;
      }
  }
  </code></pre>
  
  <p>When I set the margin to 10%, only the <code>margin-top</code> and <code>margin-left</code> work.&nbsp;&nbsp;This is not what I want.&nbsp;&nbsp;<code>margin-right</code> doesn't work at all.</p>
  
  <p>Here is the picture:</p>
  
  <p><img src="https://i.stack.imgur.com/HQxcS.jpg" alt="the picture"></p>
  
  <p>So, how can I fix this?</p>