// browser detection

var strUserAgent = navigator.userAgent.toLowerCase(); 
var isIE  = strUserAgent.indexOf("msie") > -1; 
var isNS6 = strUserAgent.indexOf("netscape6") > -1; 
var isNS7 = strUserAgent.indexOf("netscape/7") > -1; 
var isNS4 = !isIE && !isNS6 && !isNS7 && parseFloat(navigator.appVersion) < 5;
var isNS  = isNS6 || isNS7;