How to target a simple element to a tag with a class and not a template?

Question

Vue.js

Well, let's take a simple component

<template lang="jade">
div
  p {{ greeting }} World!
  OtherComponent
</template>

<script>
import OtherComponent from './OtherComponent.vue'
export default {
  components: {
    OtherComponent
  },
  data () {
    return {
      greeting: 'Hello'
    }
  }
}
</script>

<style lang="stylus" scoped>
p
  font-size 2em
  text-align center
</style>

The resulting component will only work with what lies inside the . And if I use Vue with PHP framework. And my page is rendered on the PHP side, and only after that it should be picked up by Vue. What should I do then?