script.js

    (function () {
      const second = 1000,
          minute = second * 60,
          hour = minute * 60,
          day = hour * 24;

      //I'm adding this section so I don't have to keep updating this pen every year :-)
      //remove this if you don't need it
      let today = new Date(),
          dd = String(today.getDate()).padStart(2, "0"),
          mm = String(today.getMonth() + 1).padStart(2, "0"),
          yyyy = today.getFullYear(),
          nextYear = yyyy + 1,
    dayMonth = "04/02/ ",
          birthday = dayMonth + yyyy;

      today = mm + "/" + dd + "/" + yyyy;
      if (today > birthday) {
          birthday = dayMonth + nextYear;
      }
      //end

      const countDown = new Date(birthday).getTime(),
          x = setInterval(function () {

              const now = new Date().getTime(),
                  distance = countDown - now;

              document.getElementById("days").innerText = Math.floor(distance / (day)),
                  document.getElementById("hours").innerText = Math.floor((distance % (day)) / (hour)),
                  document.getElementById("minutes").innerText = Math.floor((distance % (hour)) / (minute)),
                  document.getElementById("seconds").innerText = Math.floor((distance % (minute)) / second);

              //do something later when date is reached
              if (distance < 0) {
                  document.getElementById("headline").innerText = "ltdh22{t1Ck_T0Ck_B1sH}";
                  document.getElementById("countdown").style.display = "none";
                  document.getElementById("content").style.display = "block";
                  clearInterval(x);
              }
              //seconds
          }, 0)
  }());