添加自动生成CSS3浏览器平台样式功能。

webpack文件添加配置：

  module: {//模块
    rules: [//规则，多个loader
      {
        test: /\.styl$/,//匹配到styl结尾的文件，加载stylus-loader，
        use: [
          MiniCssExtractPlugin.loader,//抽离成css文件，用link形式链接
          "css-loader",
          "postcss-loader",
          "stylus-loader"
        ]
      },
    ]
  }

运行npm run dev

发现有报错：

ERROR in ./src/index.styl
Module build failed (from ./node_modules/mini-css-extract-plugin/dist/loader.js):
ModuleBuildError: Module build failed (from ./node_modules/postcss-loader/src/index.js):
Error: No PostCSS Config found in: /Users/maomao/Documents/demo/h5/mm_webpack/src
    at /Users/maomao/Documents/demo/h5/mm_webpack/node_modules/postcss-load-config/src/index.js:91:15
    at processResult (/Users/maomao/Documents/demo/h5/mm_webpack/node_modules/webpack/lib/NormalModule.js:598:19)
    at /Users/maomao/Documents/demo/h5/mm_webpack/node_modules/webpack/lib/NormalModule.js:692:5
    at /Users/maomao/Documents/demo/h5/mm_webpack/node_modules/loader-runner/lib/LoaderRunner.js:399:11
    at /Users/maomao/Documents/demo/h5/mm_webpack/node_modules/loader-runner/lib/LoaderRunner.js:251:18
    at context.callback (/Users/maomao/Documents/demo/h5/mm_webpack/node_modules/loader-runner/lib/LoaderRunner.js:124:13)
    at /Users/maomao/Documents/demo/h5/mm_webpack/node_modules/postcss-loader/src/index.js:208:9
 @ ./src/aaa.js 4:0-23

1 ERROR in child compilations
webpack 5.21.2 compiled with 2 errors in 732 ms
ℹ ｢wdm｣: Failed to compile.

提示没有PostCSS Config文件。

于是，

创建postcss.config.js文件，并编辑：

module.exports = {
    plugins: [require("autoprefixer")]
}

然后继续运行：npm run dev

问题解决。