mybb board close (Countdown)

<style>
.refreshButton {
    background-color: #1A1A1A;
    border: none;
    color: #fff;
    padding: 8px 16px;
    text-align: center;
    display: inline-block;
    transition-duration: 0.4s;
    border: 2px solid #005F82;
  }

  .refreshButton:hover {
    background-color: #0077A3;
    color: #fff;
    border: 2px solid #1A1A1A;
  }
</style>

<center><h2>We are currently closed for maintenance, check back when the timer runs out!</h2><h2 id="countdown">0d 0h 00m 00s</h2></center>

<script>
// Countdown Date
var countDownDate = new Date("Mar 30, 2020 05:35:25").getTime();

var x = setInterval(function() {
  var now = new Date().getTime();
  var distance = countDownDate - now;

  var days = Math.floor(distance / (1000 * 60 * 60 * 24));
  var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
  var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
  var seconds = Math.floor((distance % (1000 * 60)) / 1000);

  document.getElementById("countdown").innerHTML = days + "d " + hours + "h "
  + minutes + "m " + seconds + "s ";

  if (distance < 0) {
    clearInterval(x);
    document.getElementById("countdown").innerHTML = "<input class=\"refreshButton\" type=\"button\" value = \"Refresh\" onclick=\"history.go(0)\" />";
  }
}, 1000);
</script>