$(document).ready(function()
         {
            var pContainer = document.getElementById( 'container' );
            var iWidth = pContainer.offsetWidth;
            var iHeight = pContainer.offsetHeight;

            var iHeightTmp = iHeight/2;
            var iWidthTmp = iWidth/2;
            
            var sHeightTmp = '-' + iHeightTmp + 'px';
            var sWidthTmp = '-' + iWidthTmp + 'px';

            $( '#container' ).css(
            {
               'position': 'absolute', 'top': '50%', 'margin-top': sHeightTmp, 'left': '50%', 'margin-left': sWidthTmp
            });
         });