window.onload = function() {

    $(document).ready(function() {

        var hgt = $('#container');
        var bgt = $('#container .dopis1');

        var bgtHalfW = bgt.width()/2;
        var bgtHalfH = bgt.height()/2;

        hgt.mousemove(function(event){
	    event.preventDefault();
            bgt.show();
            var scrollLeftPos = $(window).scrollLeft();
            var scrollTopPos = $(window).scrollTop();
            var offsetLft = hgt.offset().left;
            var offsetTp = hgt.offset().top;
            var upX = event.clientX;
            var upY = event.clientY;
            bgt.css({backgroundPosition : ''+(offsetLft-upX+bgtHalfW-scrollLeftPos)+'px '+(offsetTp-upY+bgtHalfH-scrollTopPos)+'px',top:''+(-offsetTp+upY-bgtHalfH+scrollTopPos)+'px',left:''+(-offsetLft+upX-bgtHalfW+scrollLeftPos)+'px'});
        });

        hgt.mouseout(function(){
            bgt.hide();
        });

    });


};