var speed=150

pro_demo2.innerHTML=pro_demo1.innerHTML 
function Marquee(){ 
var mm_mo = pro_demo.offsetHeight - pro_demo1.offsetHeight;
if(mm_mo<0) mm_mo=0;
if(pro_demo2.offsetHeight-pro_demo.scrollTop<=mm_mo) 
pro_demo.scrollTop-=pro_demo1.offsetHeight 
else{ 
pro_demo.scrollTop+=5
} 
} 
var MyMar=setInterval(Marquee,speed) 
pro_demo.onmouseover=function() {clearInterval(MyMar)} 
pro_demo.onmouseout=function() {MyMar=setInterval(Marquee,speed)}