webpack.base.conf.js 中的

{
    test: /\.vue$/,
    loader: 'vue-loader',
    options: {
      loaders: {
        css: ['vue-style-loader',
          { loader: 'css-loader', options: { sourceMap: false } }
        ],
        less: ['vue-style-loader',
          { loader: 'css-loader', options: { sourceMap: false } },
          { loader: 'less-loader', options: { sourceMap: false } }
        ],
        // 第 1 處
        postcss: ['vue-style-loader',
          { loader: 'css-loader', options: { sourceMap: false } }
        ],
      }
    },
    cssSourceMap: false,
    cacheBusting: true,
    transformToRequire: {
        video: ['src', 'poster'],
        source: 'src',
        img: 'src',
        image: 'xlink:href'
     }
},

webpack.dev.config.js

rules: [
      {
        test: /\.css$/,
        use: [
          { loader: 'vue-style-loader' },
          { loader: 'css-loader', options: { sourceMap: true } },
          // 第 2 處
          { loader: 'postcss-loader', options: { sourceMap: true } }
        ]
      }
    ]

以上兩處配置使用postcss分別做了什么？有什么區(qū)別？

還有：根目錄下的.postcssrc.js是這兩處的共用postcss配置嗎，還是.....

module.exports = {
  "plugins": {
    // to edit target browsers: use "browserslist" field in package.json
    "postcss-import": {},
    "autoprefixer": {}
  }
}