if (navigator.browserLanguage.indexOf("en") > -1) {
location.href="sprachen/en/index.html";
} else if (navigator.browserLanguage.indexOf("pl") > -1) {
location.href="sprachen/pl/index.html";
} else if (navigator.browserLanguage.indexOf("cs") > -1) {
location.href="sprachen/cz/index.html";
} else if (navigator.browserLanguage.indexOf("cz") > -1) {
location.href="sprachen/cz/index.html";
}