[Vuejs]-Vuejs nested foreach loop not working

It should be following, as mark is an element inside word:

<div id="app">
  <p>{{ message }}</p>
  <span v-for="word in words">
      {{word.name}} <br/>
      {{word.id}} <br/>
    <span v-for="mark in word.marks">
          {{mark}} 
    </span>
    <br/>
  </span>
</div>