Examine source code of Rouming.cz improve UI

{
  "update_url": "https://clients2.google.com/service/update2/crx",
  "manifest_version": 2,
  "name": "Rouming.cz improve UI",
  "description": "Extension for improve IU for better UX on website Roumenův rouming (https://rouming.cz/)",
  "version": "1.8.0",
  "permissions": [
    "storage"
  ],
  "author": "Jakub Bouček",
  "homepage_url": "https://github.com/jakubboucek/roumen-cz-improve-ui",
  "short_name": "Improve rouming.cz",
  "icons": {
    "16": "rouming_16.png",
    "48": "rouming_48.png",
    "128": "rouming_128.png"
  },
  "browser_action": {
    "default_icon": {
      "16": "rouming_16.png",
      "48": "rouming_48.png",
      "128": "rouming_128.png"
    },
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.rouming.cz/*",
        "*://www.roumenovomaso.cz/*"
      ],
      "css": [
        "roumen.css"
      ],
      "js": [
        "roumen.js"
      ],
      "run_at": "document_end"
    }
  ],
  "web_accessible_resources": [
    "expand.svg"
  ]
}