Thanks for this Nancy. It seems that it will only work with percentages. perhaps there is someway I can get screen res and calculate.
Sadly no. Screen resolution sniffer scripts can't tell if the browser's viewport is maximized or not. Neither can they tell how many browser toolbars are displayed. Thus the only way to accurately center web pages vertically is with percentages.
That said, you can fake vertical centering by adding margin-top values to the body tag.