如何在vue-cli 3中设置CSS背景？

npm install sass-loader node-sass --save-dev

module.exports = {
  css: {
    loaderOptions: {
      sass: {
        prependData: `@import "@/assets/styles/variables.scss";`
      }
    }
  }
}

$background-color: #f0f0f0;

body {
  background-color: $background-color;
}

<template>
  <div class="app">
    <!-- 页面内容 -->
  </div>
</template>

<style lang="scss">
.app {
  background-color: $background-color;
}
</style>