.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,0.5);
  display: none;
  align-items: center;
  justify-content: center;
  z-index: 9999;
}
.modal {
  background: #fff;
  width: min(520px, 92vw);
  border-radius: 5px;
  box-shadow: 0 10px 30px rgba(0,0,0,0.3);
  padding: 24px 20px;
  text-align: center;
}
.modal .countdown {
  font-weight: bold;
}