.slide {
  width: 60vw;
  height: 40vw;
  overflow: hidden;
  position: relative;
  background-color: rgb(51, 204, 255);
}
.slide > div {
  width: 100%;
  height: 100%;
  background-size: cover;
  position: absolute;
  animation: slide 21s infinite;
  opacity: 0;
}
.slide > div:nth-child(2) {
  animation-delay: 7s;
}
.slide > div:nth-child(3) {
  animation-delay: 14s;
}
@keyframes slide {
  15% {
    opacity: 1;
  }
  25% {
    opacity: 1;
  }
  35% {
    opacity: 0;
  }
  40% {
    transform: scale(1.3);
  }
}