A、animation

<template>
     <transition>
         <slot></slot>
     </transition>
</template>
<script>
export default {
}
</script>
<style>
.v-enter-active {
  animation: bounce-in .5s;
}
.v-leave-active {
  animation: bounce-in .5s reverse;
}
@keyframes bounce-in {
  0% {
    opacity: 0;
  }
  50% {
    opacity: 0.5;
  }
  100% {
    opacity: 1;
  }
}
</style>