body {
  margin: 0;
  background-color: black;
  overflow: hidden;
}

canvas {
  display: block;
}

#envelopeButton {
  position: fixed;
  top: 65%;
  left: 45%;
  padding: 10px 20px;
  font-size: 20px;
  border-radius: 10px;
  background-color: #d6336c;
  color: white;
  border: none;
  cursor: pointer;
  box-shadow: 2px 4px 6px rgba(0, 0, 0, 0.1);
  animation: fadeInUp 1s ease forwards;
  animation-delay: 5s;
}

/* animation (if not added yet) */
@keyframes fadeInUp {
  to {
    opacity: 1;
    transform: translateY(0);
  }
}