Examine source code of Full Width Pages

{
  "browser_specific_settings": {
    "gecko": {
      "id": "mr.zhukovsky02@gmail.com",
      "strict_min_version": "109.0"
    }
  },
  "name": "Full Width Pages",
  "description": "Page wider",
  "icons": {
    "16": "./assets/icon_16x16.png",
    "32": "./assets/icon_32x32.png",
    "48": "./assets/icon_48x48.png",
    "128": "./assets/icon_128x128.png"
  },
  "version": "2.0",
  "manifest_version": 3,
  "permissions": [
    "activeTab",
    "scripting",
    "storage",
    "tabs"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "commands": {
    "toggle-site-wide": {
      "suggested_key": {
        "default": "Alt+Shift+W"
      },
      "description": "Toggle Wider for current site"
    },
    "toggle-always-on": {
      "suggested_key": {
        "default": "Alt+Shift+A"
      },
      "description": "Toggle always-on mode"
    }
  },
  "action": {
    "default_title": "Full Width Pages",
    "default_icon": {
      "16": "./assets/icon_16x16.png",
      "32": "./assets/icon_32x32.png",
      "48": "./assets/icon_48x48.png",
      "128": "./assets/icon_128x128.png"
    },
    "default_popup": "./popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}