Change list card to grid card

index.vue

<template>
  <div class="mt-5">
    <div class="container">
      <div class="card-columns">
        <div class="card" v-for="item in posts" v-bind:key="item.key">
          <img class="card-img-top" :src="item.urlToImage" alt="Card image cap">
          <div class="card-body">
            <p class="card-text"><small class="text-muted">{{ item.author }} - {{ item.source.name }}</small></p>
            <h5 class="card-title">{{ item.title }}</h5>
            <p class="card-text"><small class="text-muted">{{ item.publishedAt }}</small></p>
          </div>
        </div>        
      </div>
    </div>
  </div>
</template>