<div class="countdown-timer">
  <div class="time-box">
    <span class="num" id="days">05</span>
    <span class="label">Days</span>
  </div>
  <div class="time-box">
    <span class="num" id="hours">12</span>
    <span class="label">Hours</span>
  </div>
  <div class="time-box">
    <span class="num" id="mins">45</span>
    <span class="label">Mins</span>
  </div>
  <div class="time-box">
    <span class="num" id="secs">30</span>
    <span class="label">Secs</span>
  </div>
</div>

.countdown-timer {
  font-family: system-ui, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
  display: flex;
  gap: 15px;
}
.time-box {
  display: flex;
  flex-direction: column;
  align-items: center;
  background: #1f2937;
  color: white;
  padding: 15px 20px;
  border-radius: 12px;
  min-width: 80px;
  box-shadow: 0 4px 10px rgba(0,0,0,0.1);
}
.num {
  font-size: 2rem;
  font-weight: 700;
  line-height: 1;
  margin-bottom: 5px;
}
.label {
  font-size: 0.75rem;
  text-transform: uppercase;
  letter-spacing: 1px;
  opacity: 0.8;
}

const d = document.getElementById("days");
const h = document.getElementById("hours");
const m = document.getElementById("mins");
const s = document.getElementById("secs");

const timer = setInterval(() => {
  let days = parseInt(d.innerText);
  let hours = parseInt(h.innerText);
  let mins = parseInt(m.innerText);
  let secs = parseInt(s.innerText);

  if (secs > 0) {
    secs--;
  } else if (mins > 0) {
    secs = 59;
    mins--;
  } else if (hours > 0) {
    secs = 59;
    mins = 59;
    hours--;
  } else if (days > 0) {
    secs = 59;
    mins = 59;
    hours = 23;
    days--;
  }

  d.innerText = days < 10 ? "0" + days : days;
  h.innerText = hours < 10 ? "0" + hours : hours;
  m.innerText = mins < 10 ? "0" + mins : mins;
  s.innerText = secs < 10 ? "0" + secs : secs;
}, 1000);