.result {
  text-align: center;
  font-size: 40px;
}

function countDown() {
  var deadline = new Date().getTime() + 24 * 60 * 60 * 1000; // give a unix timestamp

  var result = "";

  setInterval(() => {
    var now = new Date().getTime();
    var t = deadline - now;
    var days = Math.floor(t / (1000 * 60 * 60 * 24));
    var hours = Math.floor((t % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
    var minutes = Math.floor((t % (1000 * 60 * 60)) / (1000 * 60));
    var seconds = Math.floor((t % (1000 * 60)) / 1000);
    if (t < 0) {
      clearInterval();
      days = 0;
      hours = 0;
      minutes = 0;
      seconds = 0;
    }
    result = days + " days " + hours + " h " + minutes + " m " + seconds + " s";
    document.querySelector(".result").innerText = result;
  }, 1000);
}

countDown();