var xV1 = 0;

    function stayHome(){    

        nV = document.body.scrollTop;    
        document.getElementById('isFloat1').style.top = xV1+nV;
    }

    function init(){

        xV1 = document.getElementById('isFloat1').offsetTop;
    }

    window.onload=init;
    window.onscroll=stayHome;