CompA.vue

<template>
  <div class="wrapper">
    <comp-b>...</comp-b>
  </div>
</template>

<script>
import CompB from 'xxx/CompB'

export default {
  components: {
    CompB
  }
}
</script>

<style>
  .wrapper .compb-header {
    color: red;
  }
</style>