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

.fade-in-image {
    animation: fadeIn 3s;
    -webkit-animation: fadeIn 3s;
    -moz-animation: fadeIn 3s;
    -o-animation: fadeIn 3s;
    -ms-animation: fadeIn 3s;
  }

  @keyframes fadeIn {
    0% {opacity:0;}
    100% {opacity:1;}
  }
  
  @-moz-keyframes fadeIn {
    0% {opacity:0;}
    100% {opacity:1;}
  }
  
  @-webkit-keyframes fadeIn {
    0% {opacity:0;}
    100% {opacity:1;}
  }
  
  @-o-keyframes fadeIn {
    0% {opacity:0;}
    100% {opacity:1;}
  }
  
  @-ms-keyframes fadeIn {
    0% {opacity:0;}
    100% {opacity:1;}
  }