Webpacker 3.5不提供CSS。 Rails 5.2.2

Question

我在Rails 5.2.2应用程序中有gem 'webpacker', '~> 3.5'，但是当在.bin/webpack-dev-server的单独终端中运行rails s时，我看不到我的/app/CSS/文件夹中的任何样式，只是localhost:3000上的纯文本。 localhost:3035只是展示了cannot GET/。我在应用程序或控制台中没有收到任何错误。 $.bin/webpack-dev-server是正确的终端命令吗？

application.html.erb

  <%= javascript_pack_tag 'application' %> 
  <%= stylesheet_pack_tag 'application', media: 'all' %>

的JavaScript /包/的application.js

import '../css/simple-grid.css';
import '../css/application.css'

webpacker.yml

default: &default
  source_path: app/javascript
  source_entry_path: packs
  public_output_path: packs
  cache_path: tmp/cache/webpacker

  # Additional paths webpack should lookup modules
  # ['app/assets', 'engine/foo/app/assets']
  resolved_paths: []

  # Reload manifest.json on all requests so we reload latest compiled packs
  cache_manifest: false

  extensions:
    - .js
    - .sass
    - .scss
    - .css
    - .module.sass
    - .module.scss
    - .module.css
    - .png
    - .svg
    - .gif
    - .jpeg
    - .jpg

development:
  <<: *default
  compile: true

  # Reference: https://webpack.js.org/configuration/dev-server/
  dev_server:
    https: false
    host: localhost
    port: 3035
    public: localhost:3035
    hmr: true
    # Inline should be set to true if using HMR
    inline: true
    overlay: true
    compress: true
    disable_host_check: true
    use_local_ip: false
    quiet: false
    headers:
      'Access-Control-Allow-Origin': '*'
    watch_options:
      ignored: /node_modules/


test:
  <<: *default
  compile: true

  # Compile test packs to a separate directory
  public_output_path: packs-test

production:
  <<: *default

  # Production depends on precompilation of packs prior to booting for performance.
  compile: false

  # Cache manifest.json for performance
  cache_manifest: true

的package.json

{
  "name": "GD",
  "private": true,
  "dependencies": {
    "@rails/webpacker": "3.5",
    "autoprefixer": "^9.4.5",
    "axios": "^0.18.0",
    "babel-preset-react": "^6.24.1",
    "prop-types": "^15.6.2",
    "react": "^16.7.0",
    "react-autosize-textarea": "^6.0.0",
    "react-dom": "^16.7.0",
    "react-responsive-navbar": "^1.0.11",
    "react-select": "^2.3.0",
    "webpack-cli": "^3.2.3"
  },
  "devDependencies": {
    "webpack-dev-server": "2.11.2"
  }
}

我在控制台中没有错误，它告诉我webpack Compiled Successfully：

^CSimons-MBP-2:GD Simon$ ./bin/webpack-dev-server
Project is running at http://localhost:3035/
webpack output is served from /packs/
Content not from webpack is served from /Users/Simon/Sites/GD/public/packs
404s will fallback to /index.html
Hash: 1b5e7c9ec1725de169c0
Version: webpack 3.12.0
Time: 2444ms
                                  Asset       Size  Chunks                    Chunk Names
    application-1b5e7c9ec1725de169c0.js     436 kB       0  [emitted]  [big]  application
application-1b5e7c9ec1725de169c0.js.map     495 kB       0  [emitted]         application
                          manifest.json  142 bytes          [emitted]
   [0] multi (webpack)-dev-server/client?http://localhost:3035 webpack/hot/dev-server ./app/javascript/packs/application.js 52 bytes {0} [built]
[./app/javascript/css/application.css] ./app/javascript/css/application.css 1.34 kB {0} [built]
[./app/javascript/css/simple-grid.css] ./app/javascript/css/simple-grid.css 1.34 kB {0} [built]
[./app/javascript/packs/application.js] ./app/javascript/packs/application.js 538 bytes {0} [built]
[./node_modules/loglevel/lib/loglevel.js] ./node_modules/loglevel/lib/loglevel.js 7.86 kB {0} [built]
[./node_modules/strip-ansi/index.js] ./node_modules/strip-ansi/index.js 161 bytes {0} [built]
[./node_modules/url/url.js] ./node_modules/url/url.js 23.3 kB {0} [built]
[./node_modules/webpack-dev-server/client/index.js?http://localhost:3035] (webpack)-dev-server/client?http://localhost:3035 7.93 kB {0} [built]
[./node_modules/webpack-dev-server/client/overlay.js] (webpack)-dev-server/client/overlay.js 3.67 kB {0} [built]
[./node_modules/webpack-dev-server/client/socket.js] (webpack)-dev-server/client/socket.js 1.08 kB {0} [built]
[./node_modules/webpack/hot ^\.\/log$] (webpack)/hot nonrecursive ^\.\/log$ 170 bytes {0} [built]
[./node_modules/webpack/hot/dev-server.js] (webpack)/hot/dev-server.js 1.61 kB {0} [built]
[./node_modules/webpack/hot/emitter.js] (webpack)/hot/emitter.js 77 bytes {0} [built]
[./node_modules/webpack/hot/log-apply-result.js] (webpack)/hot/log-apply-result.js 1.31 kB {0} [built]
[./node_modules/webpack/hot/log.js] (webpack)/hot/log.js 1.04 kB {0} [built]
    + 20 hidden modules
webpack: Compiled successfully.

某处显然出现了问题，但没有任何错误信息，我无法发现问题所在。