大佬們，為什么我這樣寫沒有看到壓縮好的css文件呢？html和js文件都成功的壓縮了，存進了dist文件夾

var path = require('path');
var htmlwebpackplugin = require('html-webpack-plugin');
var ExtractTextPlugin = require('extract-text-webpack-plugin');
var webpack = require('webpack');

var ROOT_PATH = path.resolve(__dirname);
var BUILD_PATH = path.resolve(ROOT_PATH,'dist');

module.exports = {
    entry: './js/main.js',
    output: {
        filename: 'bundle.js',
        path: BUILD_PATH
    },
    module: {
        rules: [
            {
                test: /(\.jsx|\.js)$/,
                use: {
                    loader: "babel-loader"
                },
                exclude: /node_modules/
            }, 
            {
                test: /\.css$/,
                use: ExtractTextPlugin.extract({
                    fallback: "style-loader",
                    use: [
                        {
                            loader: "css-loader",
                            options: {
                                modules: true,
                                minimize: true
                            }
                        }
                    ],
                })
            },
            {
                test: /\.less$/,
                use: ExtractTextPlugin.extract({
                    fallback: "style-loader",
                    use: [
                        {
                            loader: "less-loader",
                            options: {
                                modules: true,
                                minimize: true
                            }
                        }
                    ],
                })
            },
        ]
    },
    plugins: [
        new htmlwebpackplugin({
            template: './index.html',
            hash: true,
            minify: { //壓縮HTML文件
                removeComments: true, //移除HTML中的注釋
                collapseWhitespace: true //刪除空白符與換行符
            }
        }),
        new webpack.optimize.UglifyJsPlugin({  //壓縮js
           compress: {
               warnings: false
           },
           except: ['$super','$','exports','require'] //排除關鍵字
        }),
        new ExtractTextPlugin('./css/css.css')
    ]
};