//order matters
	var browser;
	if( window.navigator.userAgent.toLowerCase().indexOf('gecko') != -1 )
		browser ='gecko';
	else if( window.navigator.userAgent.toLowerCase().indexOf('opera') != -1 )
		browser = 'opera';
	else if( window.navigator.userAgent.toLowerCase().indexOf('msie') != -1 )
		browser = 'ms';
	else if( window.navigator.userAgent.toLowerCase().indexOf('mozilla') != -1 )
		browser = 'nn4';
	else
		browser = 'unknown';