How to set Menu Size according to Browser in Java Script

function setMenuSize()

{

var mfund = document.getElementById("Mfund");

var brow=((navigator.appName) +

(parseInt(navigator.appVersion)));

//if(parseInt(navigator.appVersion >=4))

//{

if(brow == "Microsoft Internet Explorer4")

{

//alert('hi');

document.getElementById("a2").style.width = '150px';

}

}