.popup {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.7);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 999;
}

.popup-content {
  background: white;
  padding: 30px;
  border-radius: 10px;
  text-align: center;
  max-width: 400px;
  width: 90%;
  position: relative;
}

.close-btn {
  position: absolute;
  right: 15px;
  top: 10px;
  font-size: 20px;
  cursor: pointer;
}

#countdown {
  font-size: 24px;
  font-weight: bold;
  margin-top: 15px;
}