countdown.html

<div style="background-color: #000000;color:#FFFF00; font-size: 85px; font-weight: normal">
	<center>
		Nome do Evento -  Faltam
		<div id="dday"></div>
	</center>
</div>
<script>
	var countDownDate = new Date("April 25, 2022 12:00:00").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("dday").innerHTML = days + " dias " + hours + ":"
  		+ minutes + ":" + seconds + "s";

  		if (distance < 0) {
    		clearInterval(x);
    		document.getElementById("dday").innerHTML = "EVENTO JÁ ACONTECEU!";
  		}
	}, 1000);
</script>