.slideBox {
  height: 350px;
  overflow: hidden;
  position: relative;
}

/* imgのみ */
.item1 {
  opacity: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  position: absolute;
  left: 0;
  top: 0;
  -webkit-animation: anime 40s 0s infinite;
  animation: anime 40s 0s infinite;
}

.item1:nth-of-type(2) {
  -webkit-animation-delay: 10s;
  animation-delay: 10s;
}

.item1:nth-of-type(3) {
  -webkit-animation-delay: 20s;
  animation-delay: 20s;
}

.item1:nth-of-type(4) {
  -webkit-animation-delay: 30s;
  animation-delay: 30s;
}

/* ふわっとアニメーション */
@keyframes anime {
  0% {
    opacity: 0;
  }
  20% {
    opacity: 1;
  }
  25% {
    opacity: 1;
  }
  40% {
    opacity: 0;
    z-index: 9;
  }
  100% {
    opacity: 0;
  }
}

@-webkit-keyframes anime {
  0% {
    opacity: 0;
  }
  20% {
    opacity: 1;
  }
  25% {
    opacity: 1;
  }
  40% {
    opacity: 0;
    z-index: 9;
  }
  100% {
    opacity: 0;
  }
}