Examine source code of CSS Breakpoint Button

{
  "manifest_version": 3,
  "name": "CSS Breakpoint Button",
  "version": "0.5.0",
  "description": "Automatically detects and displays active breakpoints and viewport width for any site.",
  "default_locale": "en",
  "homepage_url": "https://css.usefulapps.cloud",
  "icons": {
    "16": "icons/16.png",
    "19": "icons/19.png",
    "38": "icons/38.png",
    "48": "icons/48.png",
    "96": "icons/96.png",
    "128": "icons/128.png"
  },
  "action": {
    "default_popup": "src/popup/index.html",
    "default_title": "CSS Breakpoint Button",
    "default_icon": {
      "19": "icons/19.png",
      "38": "icons/38.png"
    }
  },
  "background": {
    "service_worker": "src/background.service-worker.js",
    "scripts": [
      "src/background.service-worker.js"
    ]
  },
  "host_permissions": [
    "<all_urls>"
  ],
  "permissions": [
    "storage",
    "activeTab",
    "scripting"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "src/content-scripts/content-script.js"
      ]
    },
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "src/content-scripts/main-world-state.js"
      ],
      "world": "MAIN"
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "assets/*.css",
        "assets/*.js",
        "src/content-scripts/detect.js"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "webext@divordie.com",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}