how to use postcss, in vue-cli3 to ignore a folder and not let it affect the style inside?

the vue.config.js code is as follows

css: { // chainWebpackcss loader
modules: false, //  "foo.module.css" 
extract: true, // css ExtractTextPlugin<style>            html
sourceMap: false, // false
loaderOptions: { // css
  css: {
    localIdentName: "[name]-[hash]",
    camelCase: "only"
  },
  postcss: {
      // test: /\.css$/,
      // loader: "postcss",
      // exclude: path.resolve(__dirname,"/node_modules/"),
  },
  stylus: {}
}

},
ask the boss for answers