<div>
    <div class="demo">
        <div class="child"></
        div>
    </div>
</div>
<script>
// some code
<script/>
<style lang="less" scoped>
  .demo {
    height: 100px;
    padding-top: 20px;
    background-color: grey;
    /deep/.child {
      color: red;
    }
  }
</style>

//test.less
.demo {
    height: 100px;
    padding-top: 20px;
    background-color: grey;
    :global(.child) {
        color: red
    }
}

import styles from './test.less'

// some code

<div className={styles.demo}>
    <div class="child"></div>
</div>

module.exports = {
  chainWebpack: (config) => {
    config.devServer
      .proxy({
        '/api': {
          target: 'http://localhost:3000',
          pathRewrite: { '^/api': '', },
        },
      })
      .port(9000);

    config.module
    .rule('less')
    .oneOf('normal-modules')
    .test(/.less$/)
    .use('css-loader')
    .tap(options => {
      return Object.assign(options, {
        modules: {
          localIdentName: '[name]__[local]___[hash:base64:5]',
          auto: /\.less$/i,
        },
      })
    });

  },
};