.modal {
  display: none; 
  position: fixed; 
  z-index: 999; 
  left: 0;
  top: 0;
  width: 100%; 
  height: 100%; 
  overflow: auto; 
  background-color: rgba(0,0,0,0.4); 
}
.modal-content {
  background-color: #fff;
  margin: 15% auto; 
  padding: 20px;
  border: 1px solid #888;
  width: 90%;
  max-width: 400px;
  border-radius: 8px;
  text-align: center;
}
.close {
  color: #aaa;
  float: right;
  font-size: 28px;
  font-weight: bold;
  cursor: pointer;
}
input[type="email"] {
  width: 90%;
  padding: 10px;
  margin-top: 10px;
}
button {
  padding: 10px 20px;
  margin-top: 10px;
}