Examine source code of Dark Connect

{
  "manifest_version": 3,
  "name": "Dark Connect - Dark Mode for Garmin Connect",
  "short_name": "Dark Connect",
  "version": "2.6.4",
  "description": "Dark mode for Garmin Connect website that replaces light colors with their dark theme.",
  "permissions": [
    "notifications",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://connect.garmin.com/*",
        "https://livetrack.garmin.com/*",
        "https://live.garmin.com/*"
      ],
      "exclude_matches": [
        "https://connect.garmin.com/",
        "https://connect.garmin.com/signin/*",
        "https://connect.garmin.com/start/*",
        "https://connect.garmin.com/support/*",
        "https://connect.garmin.com/status/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "styles/main.css",
        "styles/modal.css"
      ],
      "matches": [
        "*://*.garmin.com/*"
      ]
    }
  ],
  "action": {
    "default_popup": "popup.html",
    "default_title": "Dark Connect Info",
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "dark-connect@kpulka.com",
      "strict_min_version": "109.0"
    }
  }
}