animate.css/source/rotating_entrances/rotateInDownLeft.css

@keyframes rotateInDownLeft {
  0% {
    transform-origin: left bottom;
    transform: rotate3d(0, 0, 1, -45deg);
    opacity: 0;
  }

  100% {
    transform-origin: left bottom;
    transform: none;
    opacity: 1;
  }
}

.rotateInDownLeft {
  animation-name: rotateInDownLeft;
}