function startCountdown() {
    const beep = new Audio("/static/sounds/beep.wav");
    const go = new Audio("/static/sounds/go.wav");

    setTimeout(() => {
        document.getElementById("licht1").classList.add("aktiv");
        beep.play();
    }, 1000);

    setTimeout(() => {
        document.getElementById("licht2").classList.add("aktiv");
        beep.play();
    }, 2000);

    setTimeout(() => {
        document.getElementById("licht3").classList.add("aktiv");
        beep.play();
    }, 3000);

    setTimeout(() => {
        document.querySelectorAll(".licht").forEach(el => {
            el.classList.remove("rot");
            el.classList.add("gruen");
        });
        go.play();
    }, 4000);

    setTimeout(() => {
        window.location.href = "/rennen";
    }, 7000);
}