$(document).ready(function() {

  jQuery.fn.centerScreen = function(loaded) {
    var obj = this;
    var windowheight = $(window).height()/2-this.height()/2;
    /* If the window is too short, force it to center at a reasonable value */
    var minheight = 18;
    if(windowheight < minheight) {
       windowheight = minheight;
    }

    if(!loaded) {
      obj.css('top', windowheight);
      $(window).resize(function() { 
	obj.centerScreen(!loaded); });
    } else {
	obj.stop();
	obj.animate({ top: windowheight}, 500, 'easeInOutCubic');
    }
  }

});