层滚动

function scrolldivs()
{
document.getElementById("scrolldiv").style.top=document.documentElement.scrollTop+(document.documentElement.clientHeight-document.getElementById("scrolldiv").offsetHeight)/2+"px";
 document.getElementById("scrolldiv").style.left=document.documentElement.scrollLeft+(document.documentElement.clientWidth-document.getElementById("scrolldiv").offsetWidth)/2+300+"px";
}
 
 
window.onscroll=scrolldivs;
window.onresize=scrolldivs;
window.onload=scrolldivs;