.red {
  padding: 1rem;
  border: 3px solid red
}

const { createApp, ref, onMounted } = Vue;

const app = Vue.createApp({
  setup() {
    const text = Vue.ref('Hello Ray.');
    
    Vue.onMounted(() => {
      console.log(text.value)
    })
  }
});

app.mount('#app');