hugo/themes/gohugoioTheme/assets/css/_animation.css

.animated {
  animation-duration: .5s;
  animation-fill-mode: forwards;
  animation-timing-function: ease-in-out;
}

@keyframes fadeIn {
  from {
    opacity: 0;
  }

  to {
    opacity: 1;
  }
}
.fadeIn {
  animation-name: fadeIn;
}
.animated-delay-1 {
  animation-delay: 0.5s;
}