.circulo-div {
  height: 35px;
  width: 35px;
  background-color: #bbb;
  border-radius: 50%;

  display: flex;        
  justify-content: center;
  align-items: center;
  border: 1.5px solid black;
  background-color: white;
}

.modal {
  text-align: center;
}

@media screen and (min-width: 768px) { 
  .modal:before {
    display: inline-block;
    vertical-align: middle;
    content: " ";
    height: 100%;
  }
}

.modal-dialog {
  display: inline-block;
  text-align: left;
  vertical-align: middle;
}