<div id="app">
  <div v-for="s in status">
    <div v-if="s == 'YES'" class="yes">{{ s }}</div>
    <div v-else-if="s == 'NO'" class="no">{{ s }}</div>
    <div v-else class="empty">{{ s }}</div>
  </div>
</div>


new Vue({
  el: "#app",
  data: {
    status: [ "YES", "NO", "null" ]
  },
  methods: {
  }
})

body {
  background: #20262E;
  padding: 20px;
  font-family: Helvetica;
}

#app {
  background: #fff;
  border-radius: 4px;
  padding: 20px;
  transition: all 0.2s;
}

.yes {
  background-Color: green
}

.no {
  background-Color: red
}

.empty {
  background-Color: grey
}