.popup .close {
 position: absolute;
  top: 70px;
  right: 30px;
  transition: all 200ms;
  font-size: 30px;
  font-weight: bold;
  text-decoration: none;
  color: #333;
}
.popup .close:hover {
  color: #06D85F;
}
.popup .content {
  max-height: 30%;
  overflow: auto;
}

<div id="popup1" class="overlay">
    <div class="popup">
      <a class="close" href="#">&times;</a>
       <div class="content">
         <img src="./assets/map-overlay.png">
       </div>
     </div>
</div>