core/packages/vue/examples/transition/index.html

<script src="../../dist/vue.global.js"></script>
<div id="app"></div>
<script>
  Vue.createApp({
    template: `
      <div id="test"><transition><div v-if="toggle" class="test">content</div></transition></div>
      <button @click="click">button</button>
    `,
    setup:() => {
      const toggle = Vue.ref(true)
      const click = () => toggle.value = !toggle.value
      return { toggle, click }
    }
  }).mount('#app')
</script>

<style>
  .test {
    -webkit-transition: opacity 50ms ease;
    transition: opacity 50ms ease;
  }
  .group-move {
    -webkit-transition: -webkit-transform 50ms ease;
    transition: transform 50ms ease;
  }
  .v-appear, .v-enter, .v-leave-active,
  .test-appear, .test-enter, .test-leave-active,
  .hello, .bye.active,
  .changed-enter {
    opacity: 0;
  }
  .test-anim-enter-active {
    animation: test-enter 50ms;
    -webkit-animation: test-enter 50ms;
  }
  .test-anim-leave-active {
    animation: test-leave 50ms;
    -webkit-animation: test-leave 50ms;
  }
  .test-anim-long-enter-active {
    animation: test-enter 100ms;
    -webkit-animation: test-enter 100ms;
  }
  .test-anim-long-leave-active {
    animation: test-leave 100ms;
    -webkit-animation: test-leave 100ms;
  }
  @keyframes test-enter {
    from { opacity: 0 }
    to { opacity: 1 }
  }
  @-webkit-keyframes test-enter {
    from { opacity: 0 }
    to { opacity: 1 }
  }
  @keyframes test-leave {
    from { opacity: 1 }
    to { opacity: 0 }
  }
  @-webkit-keyframes test-leave {
    from { opacity: 1 }
    to { opacity: 0 }
  }
</style>