[Webpack] Module not found: Error: Cannot resolve module 'css-loader'

环境:

Windows7;
代码和教程一样;
安装的包:
style-loader babel-core babel-loader babel-plugin-transform-runtime babel-preset-es2015 babel-preset-stage-0 babel-runtime;

问题:

添加css loader后,如果再entry.js中使用require('../css/style.css')会报错:
ERROR in ./entry.js
Module not found: Error: Cannot resolve module 'css-loader'

请问这是因为我的配置问题吗?

sunnirvana
修改的评论也不能少于六个字哦!