W3Schools Tryit Editor

<template>
 <h1>Basic CSS Transition</h1>
 <button @click="this.doesRotate = true">Rotate</button>
 <div :class="{ rotate: doesRotate }"></div>
</template>
<script>
export default {
 data() {
 return {
 doesRotate: false
 }
 }
}
</script>
<style scoped>
 .rotate {
 rotate: 160deg;
 transition: rotate 1s;
 }
 div {
 border: solid black 2px;
 background-color: lightcoral;
 width: 60px;
 height: 60px;
 }
 h1, button, div {
 margin: 10px;
 }
</style> 

import { createApp } from 'vue'
import App from './App.vue'
const app = createApp(App)
app.mount('#app')