Get your own Vue server
App.vue
InfoBox.vue
GrandChild.vue
main.js
 
<template>
  <div>
    <h4>Grand Child Component</h4>
    <p>Click the button to toggle the color of the P tag in the root component.</p>
    <button v-on:click="this.$root.color='lightgreen'">Change color in root</button>
  </div>
</template>

<style scoped>
div {
  border: solid black 1px;
  padding: 10px;
  width: 100%;
  box-sizing: border-box;
}
</style>                  
http://localhost:5173/