Contador zerando quando chega na data limite.

contador-correto-zerando-no-limite-de-data

<div class="contagem">
    Faltam apenas 
		<mark><span class="numero" id="days"></span> DIAS, <span id="hours"></span> HORAS, 
		<span class="numero" id="minutes"></span> MINUTOS</mark> E <mark><span class="numero" id="seconds"></span> SEGUNDOS</mark>
  </div>

<script>
    var countDownDate = new Date("Aug 02, 2021 20:00:00").getTime();
    
    var countdown = setInterval(function() {
    
      var now = new Date().getTime();
    
      var difference = countDownDate - now;
    
      var days = Math.floor(difference / (1000 * 60 * 60 * 24));
      var hours = Math.floor((difference % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
      var minutes = Math.floor((difference % (1000 * 60 * 60)) / (1000 * 60));
      var seconds = Math.floor((difference % (1000 * 60)) / 1000);
    
      if (difference < 0) {
        clearInterval(countdown);
        days = 0, hours = 0, minutes = 0, seconds = 0;
      }
    
      document.getElementById("days").innerText = days;
      document.getElementById("hours").innerText = hours;
      document.getElementById("minutes").innerText = minutes;
      document.getElementById("seconds").innerText = seconds;
    }, 1000);
</script>