早午餐包括select2风格

Question

我有这种brunch-config.js，其中select2 @4.0.3作为依赖：

exports.config = {
  npm: {
    enabled: true,
    globals: {
      $: 'jquery',
      jQuery: 'jquery'
    }
  },
  files: {
    javascripts: {
      joinTo: {
        "js/app.js": [
          "node_modules/phoenix/priv/static/phoenix.js",
          "node_modules/phoenix_html/priv/static/phoenix_html.js",
          "node_modules/process/browser.js",
          "node_modules/jquery/dist/jquery.js",
          "node_modules/select2/dist/js/select2.js",
          "js/app.js",
        ]
      }
    },
    stylesheets: {
      joinTo: {
        "css/app.css": [
          "node_modules/select2/dist/css/select.min.css",
          "css/phoenix.css",
          "css/app.scss"
        ]
      }
    },
    templates: {
      joinTo: "js/app.js"
    }
  },

  conventions: {
    assets: /^(static)/
  },

  paths: {
    watched: ["static", "css", "js", "vendor"],
    public: "../priv/static"
  },

  plugins: {
    babel: {
      ignore: [/vendor/]
    }
  },

  modules: {
    autoRequire: {
      "js/app.js": ["js/app"]
    },
  }
};

据我所知，早午餐从我的stylesheets.joinTo中获取样式表，并在输出文件中将它们连接在一起，但输出文件app.css中缺少select2样式。