var crossobj=document.getElementById? document.getElementById("contents") : document.all.contents
var contentheight=crossobj.offsetHeight
function movedown(){
if (parseInt(crossobj.style.top)>=(contentheight*(-1)+100))
crossobj.style.top=parseInt(crossobj.style.top)-speed+"px"
movedownvar=setTimeout("movedown()",20)
}
function moveup(){
if (parseInt(crossobj.style.top)<=0)
crossobj.style.top=parseInt(crossobj.style.top)+speed+"px"
moveupvar=setTimeout("moveup()",20)
}
function getcontent_height(){
contentheight=crossobj.offsetHeight
}
window.onload=getcontent_height