var ua = navigator.userAgent.toLowerCase();
var mozillabrowser = (ua.indexOf("gecko/") != -1);
var iebrowser = (ua.indexOf("msie") > -1 && ua.indexOf("opera") == -1); 
var operabrowser = (ua.indexOf("opera") > -1); 
var av = navigator.appVersion(); 
var version = av.substring(0, av.indexOf(" ")) *1; 
var version2 = av.substring(0, av.indexOf(".")) *1;

if (mozillabrowser || operabrowser ) 
	var versionsnummer = version2; 
else if (iebrowser){
	if (version2==4 && ua.indexOf("msie 5") == -1 &&
ua.indexOf("msie 6") == -1 && ua.indexOf("msie 7") == -1) { 
	var versionsnummer = 4;
 }else if (version2==4 && ua.indexOf("msie 5") > -1) { 
 	var versionsnummer = 5; 
 }else if (version2==4 && ua.indexOf("msie 6")>-1) { 
 	var versionsnummer = 6;  
 }else if (version2==4 && ua.indexOf("msie 7")>-1) { 
 	var versionsnummer = 7; 
 }else if (version2==4 && ua.indexOf("msie 8")>-1) {
 	var versionsnummer = 8; 
 }
}//Weiterleitung
if (mozillabrowser && versionsnummer <= 2 ) {
   location.href="browser_alt/def_alt.html";
}
if (iebrowser && versionsnummer <=6 ) {
	location.href="browser_alt/def_alt.html";
}