.overlay-container {
  display: flex;
  justify-content: center;
  align-items: flex-end;
  height: 100vh;
  padding-bottom: 60px;
  position: relative;
}
.save-date-btn {
  width: 200px;
  height: 200px;
  border-radius: 50%;
  background: #FF5544;
  border: none;
  color: white;
  font-size: 42px;
  font-weight: 700;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
}
@media (max-width: 768px) {
  .save-date-btn { width: 160px; height: 160px; font-size: 32px; }
}
@media (max-width: 480px) {
  .save-date-btn { width: 130px; height: 130px; font-size: 26px; }
}
.std-modal {
  display: none;
  position: fixed;
  z-index: 9999;
  left: 0; top: 0;
  width: 100%; height: 100%;
  background: rgba(0,0,0,0.5);
}
.std-modal-content {
  background: #fff;
  margin: 5% auto;
  padding: 20px;
  border-radius: 15px;
  width: 90%;
  max-width: 600px;
}