.overlay {
  position: fixed;
  top: 0; bottom: 0;
  left: 0; right: 0;
  background: rgba(0, 0, 0, 0.8);
  transition: opacity 500ms;
  visibility: hidden;
  opacity: 0;
  font-family:arial;
}
.overlay:target {
  visibility: visible;
  opacity: 1;
}

.popup {
  margin: 10px auto;
  padding: 10px;
  background: #fff;
  border-radius: 5px;
  width: 360px;
  height: 500px;
  position: relative;
  transition: all 5s ease-in-out;
}

.popup h2 {
  margin-top: 0;
  color: #333;
  font-family: Tahoma, Arial, sans-serif;
}
.popup .close {
  position: absolute;
  top: 0px;
  right: 5px;
  transition: all 100ms;
  font-size: 50px;
  font-weight: bold;
  text-decoration: none;
  color: #333;
  padding:0 8px;
}
.popup .close:hover {
  color: white;
  background:red;
}
.popup .content {
  height: 700px;
  overflow: auto;
}

@media screen and (max-width: 700px){
  .box{
    width:100%;
  }
  .popup{
    width: 90%;
    height: 80%;
  }
}