$(document).bind( 'mousewheel', function (e) {
    var nt = $(document.body).scrollTop()-(e.deltaY*e.deltaFactor*100);
    e.preventDefault();
    e.stopPropagation();
    $(document.body).stop().animate( {
         scrollTop : nt
     } , 500 , 'easeInOutCubic' );
} )