var winW = 630, winH = 460;
var r;


if (parseInt(navigator.appVersion)>3) {
 if (navigator.appName=="Netscape") {
  winW = window.innerWidth;
  winH = window.innerHeight;
 }
 if (navigator.appName.indexOf("Microsoft")!=-1) {
  winW = document.body.offsetWidth;
  winH = document.body.offsetHeight;
 }
}

if (winH<550) {

r=document.getElementById("b");
r.style.display="none";
}