function getWindowHeight() { 
   var windowHeight = 0; 
   if (typeof(window.innerHeight) == 'number') { 
    windowHeight = window.innerHeight; 
   } 
   else { 
    if (document.documentElement && document.documentElement.clientHeight) { 
     windowHeight = document.documentElement.clientHeight; 
    } 
    else { 
     if (document.body && document.body.clientHeight) { 
      windowHeight = document.body.clientHeight; 
     } 
    } 
   } 
   return windowHeight; 
  } 
  function setContent() { 
   if (document.getElementById) { 
    var windowHeight = getWindowHeight(); 
    if (windowHeight > 0) { 
     var contentElement = document.getElementById('content'); 
     var contentHeight = contentElement.offsetHeight; 
     if (windowHeight - contentHeight > 0) { 
      contentElement.style.position = 'relative'; 
      contentElement.style.top = ((windowHeight / 2) - (contentHeight / 2)) + 'px'; 
     } 
     else { 
      contentElement.style.position = 'static'; 
     } 
    } 
   } 
  } 
  window.onload = function() { 
   setContent(); 
  } 
  window.onresize = function() { 
   setContent(); 
  }