var speed=4
//Espacio libre después del texto. Se define para cada fichero. var espacio_vacio = 200

function movedown(){
if (window.moveupvar) clearTimeout(moveupvar)
if (parseInt(crossobj.style.top)>=(contentheight*(-1)+ espacio_vacio))
crossobj.style.top=parseInt(crossobj.style.top)-speed+"px"
movedownvar=setTimeout("movedown()",20)
}

function moveup(){
if (window.movedownvar) clearTimeout(movedownvar)
if (parseInt(crossobj.style.top)<=0)
crossobj.style.top=parseInt(crossobj.style.top)+speed+"px"
moveupvar=setTimeout("moveup()",20)
}

function stopscroll(){
if (window.moveupvar) clearTimeout(moveupvar)
if (window.movedownvar) clearTimeout(movedownvar)
}

function movetop(){
stopscroll()
crossobj.style.top=0+"px"

}

function getcontent_height(){

crossobj=document.getElementById("content");
contentheight=crossobj.offsetHeight;


}

window.onload=getcontent_height