#overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(0, 0, 0, 0.8);
  z-index: 9999;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  color: white;
  font-family: sans-serif;
}
.btn {
  padding: 15px 30px;
  font-size: 20px;
  background: #007bff;
  color: white;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  margin-top: 20px;
}