title: How to find the center of the screen?
body: <p>I have  a div,I need to <strong>show this div on the center of the screen</strong> (ie viewable area) even while the user scrolled through the page.</p>
  
  <p>so its style should be (for example)</p>
  
  <pre><code>{position:fixed; top:90px; left:150 px; z-index:9999; overflow:hidden;}
  </code></pre>
  
  <p>Now i need to find the  value of left and top, so that the div will place in the center of the screen  (ie viewable area), for any page .</p>
  
  <p>How can i find the value of left &amp; top with a javascript or jquery ?</p>