var fTop; 
function scrollfloat(){ 
var temp=fTop; 
if (typeof window.pageYOffset != 'undefined') { 
   sTop = window.pageYOffset; 
} 
else if (typeof document.compatMode != 'undefined' && 
     document.compatMode != 'BackCompat') { 
   sTop = document.documentElement.scrollTop; 
} 
else if (typeof document.body != 'undefined') { 
   sTop = document.body.scrollTop; 
} 
fTop=sTop+145; 
if(temp!==sTop) {document.getElementById('myfloat').style.top=fTop+"px"; } 
} 

if(document.body.offsetWidth>800){ 	
window.onscroll=scrollfloat; 
}