$(document).ready(function(){
    jQuery.fn.center = function () {
        var top = ( $(window).height() - this.height() ) / 2+$(window).scrollTop();
        
        if(top < 210) { top = 210; }
        
        this.css("position","absolute");
        this.css('z-index',"99999");
        this.css("top", top + 'px');
        this.css("left", ( $(window).width() - this.width() ) / 2+$(window).scrollLeft() + "px");
        return this;
    }
    
    $('#banner-small').mouseover(function(){
        $('#banner-large').show()
            .center();
    });
    
    $('#banner-small').mouseout(function(){
        $('#banner-large').hide();
    });
});