.details{...}
.slick-center .details{
  opacity: 0;
  visibility: hidden;
}

.details{
...
  -webkit-transition: all 0.3s ease;  /* Android 2.1+, Chrome 1-25, iOS 3.2-6.1, Safari 3.2-6  */
          transition: all 0.3s ease;  /* Chrome 26, Firefox 16+, iOS 7+, IE 10+, Opera, Safari 6.1+  */
}
.slick-center .details{
  opacity: 0;
  visibility: hidden;
}