function popup(clickedEl){
    ifActive = document.getElementById(clickedEl).className;

    document.getElementById("produkte").className = "inactive";
    document.getElementById("leistungen").className = "inactive";
    document.getElementById("unternehmen").className = "inactive";

    if (ifActive == "inactive") {
        document.getElementById(clickedEl).className = "active";
    }
}

function langSelect(selLang){
    document.getElementById("DE").className = "lang_inactive lang_small";
    document.getElementById("EN").className = "lang_inactive lang_small";
    document.getElementById("RU").className = "lang_inactive lang_small";

    document.getElementById(selLang).className = "lang_active lang_small";
}