//browser detection
var userBrowser   = navigator.userAgent; 
var userBrowser       = userBrowser.toLowerCase();
var isExplorer        = userBrowser.indexOf("msie") > -1;
var isNetscape        = userBrowser.indexOf("netscape") > -1; 
var isFirefox         = userBrowser.indexOf("firefox") > -1; 
var isSafari          = userBrowser.indexOf("safari") > -1; 
var isMac             = userBrowser.indexOf("mac") > -1;