.center {
    margin: 0;
    position: absolute;
    top: 50%;
    left: 50%;
    margin-right: -50%;
    transform: translate(-50%, -50%);
    width: 25%;
    height: auto;
}

.fade-in-image {
  opacity: 0;
    animation: fadeInOut 5s;
  }

  @keyframes fadeInOut {
    0%   { opacity:0; }
    50%  { opacity:1; }
    100% { opacity:0; }
  }