function pruefen() {
    var f = document.forms['kontakt'];
    var email = f.email.value;
    var name = f.name.value;
    var vorname = f.vorname.value;

    var ok = 'ja';

    if (email == '') {
        f.email.style.backgroundColor = "#B0CCCC";
        ok = 'nein';
    }
    if (name == '') {
        f.name.style.backgroundColor = "#B0CCCC";
        ok = 'nein';
    }
    if (vorname == '') {
        f.vorname.style.backgroundColor = "#B0CCCC";
        ok = 'nein';
    }

    if (ok == 'nein') {
        document.getElementById('meldung').style.Color = "red";
        document.getElementById('meldung').style.visibility = "visible";
    }
    else {
        f.submit();
        document.getElementById('meldung').style.visibility = "hidden";
    }
}

function hinterlegen(f) {
    f.style.backgroundColor = "#e0e0e0";
}
function wiederweiss(f) {
    f.style.backgroundColor = "white";
}

function vs_aus(nam, bild) {
    f = document.getElementById(nam);
    f.src = bild;
}