title: checking scrolltop of a div on window's scroll event
body: <p>Please refer this <a href="http://jsfiddle.net/USDFn/" rel="nofollow">jsfiddle</a> </p>
  
  <p>I want to change css of div #fixed when its scrolltop is less than 50. but it is not checking the condition  <code>(fixedscrolltop &lt; 50)</code>  at all.</p>
  
  <p>the #fixed div should be repositioned when its offset is less than 50. not when the scroll event occurs</p>