Position absolute div in center of screen view
Use the following CSS:
.centered {
position: fixed;
top: 50%;
left: 50%;
/* bring your own prefixes */
transform: translate(-50%, -50%);
}
Change position:absolute to position: fixed and you should be good to go!
When you say position - absolute, the reference div is the parent div that has a position - relative. However if you say position -fixed, the reference is the browser's window. which is wat you want in your case.
In the case of IE6 i guess you have to use CSS Expression