function tobottom(id){
 document.getElementById(id).style.position='static'
 document.getElementById(id).style.top='0px'
 var BodyHeight=document.compatMode=='CSS1Compat' && !window.opera?document.documentElement.clientHeight:document.body.clientHeight
 var BlockTop=getTopPosition(id)
 var BlockHeight=document.getElementById(id).offsetHeight
 if(BodyHeight-BlockTop-BlockHeight>0){
  document.getElementById(id).style.position='absolute'
  document.getElementById(id).style.top=(BodyHeight-BlockHeight)+'px'
 }
}
function getTopPosition(id){
 var offsetTrail = document.getElementById(id);
 var offsetTop = 0;
 while (offsetTrail) {
  offsetTop += offsetTrail.offsetTop;
  offsetTrail = offsetTrail.offsetParent;
 }
 if (navigator.userAgent.indexOf("Mac") != -1 && 
  typeof document.body.leftMargin != "undefined") {
  offsetTop += document.body.topMargin;
 }
 return offsetTop;
}