Vue.js 애니메이션 - <transition>

1. 애니메이션을 주고싶으면 해당 요소를 <transition>으로 감싸기
    <transition> : Vue에서 제공하는 스페셜한 태그

<!-- template -->
<transition name="fade">
    <Modal
      @closeModal="isOpen = false"
      :onerooms="onerooms"
      :curOneRoomNumber="curOneRoomNumber"
      :isOpen="isOpen"
    />
</transition>

// CSS
.fade-enter-from {
  opacity: 0;
}

.fade-enter-active {
  transition: all 5s;
}

.fade-enter-to {
  opacity: 1;
}

.fade-leave-from {
  opacity: 1;
}

.fade-leave-active {
  transition: all 1s;
}

.fade-leave-to {
  opacity: 0;
}