title: center a div box in the middle of the page using css
body: <p>I want to center a div right in the middle of the page, I tried <code>top:30%</code>, but when the window is resized off the alignment.</p>
  
  <pre><code>&lt;div id=cent&gt;&lt;/div&gt;
  </code></pre>
  
  <p>Thanks
  Jean</p>