//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';