.overlay {
  font-weight: bold;
  height: 0%;
  width: 100%;
  position: fixed;
  z-index: 1;
  top: 0;
  left: 0;
  background-color: rgb(255,255,255);
  background-color: rgba(255,255,255, 0.8);
  overflow-y: hidden;
  transition: 0.5s;
}

.overlay-content {
  position: relative;
  top: 5%;
  width: 100%;
  text-align: center;
  margin-top: 30px;
}

.overlay a {
  padding: 4px;
  font-size: 6vmin;
  display: block;
  transition: 0.3s;
}

.overlay a:hover, .overlay a:focus {
}

.overlay .closebtn {
  position: absolute;
  top: 20px;
  right: 45px;
  font-size: 60px;
}

a.closebtn {color: black; }
a.closebtn:hover {  color: black; text-decoration: none; }

@media screen and (max-height: 450px) {
  .overlay {overflow-y: auto;}
  .overlay a {font-size: 20px}
  .overlay .closebtn {
  font-size: 40px;
  top: 15px;
  right: 35px;
  }
}