ns4 = (document.layers)? true:false 
ie4 = (document.all)? true:false 

function init() { 
          if (ns4) block = document.ltitle 
          if (ie4) block = ltitle.style 
} 

//navigator.appName == "Netscape"

function setPostn() { 
if (ns4) { 
    a=".top="; 
    adoc="document."; 
    docs=""; 
    b="window.pageYOffset"; 
    } 
else { 
    a=".pixelTop="; 
    adoc=""; 
    docs=".style"; 
    b="document.body.scrollTop"; 
   } 
} 
function checkPostn(height) { 
if (screen.height>768)
{

    object="obPic"; 
    c=eval(b); 
    if(c <= height) c=height; 
    eval(adoc+object+docs+a+c); 
    setTimeout("checkPostn("+height+")",5); 
	
}
}