Examine source code of NoFollow

{
  "manifest_version": 3,
  "browser_specific_settings": {
    "gecko": {
      "id": "nofollow@igor.jerosimic",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "name": "NoFollow",
  "version": "6.0.3",
  "description": "Outline nofollow links, detect nofollow and noindex meta tags on webpages. Features website filtering and custom CSS outline styles.",
  "homepage_url": "https://www.igorware.com/extensions/nofollow?referrer-ver=firefox-ext-manager",
  "author": "Igor Jerosimić",
  "developer": {
    "name": "Igor Jerosimić",
    "url": "https://www.igorware.com/extensions/nofollow"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "icons": {
    "16": "images/icon-016.png",
    "19": "images/icon-019.png",
    "32": "images/icon-032.png",
    "38": "images/icon-038.png",
    "48": "images/icon-048.png",
    "64": "images/icon-064.png",
    "128": "images/icon-128.png"
  },
  "action": {
    "default_title": "NoFollow",
    "default_popup": "popup.html",
    "default_icon": {
      "16": "images/icon-016.png",
      "19": "images/icon-019.png",
      "32": "images/icon-032.png",
      "38": "images/icon-038.png"
    }
  },
  "commands": {
    "toggle-active-website": {
      "description": "Toggle state for active website"
    },
    "toggle-temporary": {
      "description": "Toggle temporary state"
    }
  },
  "content_scripts": [
    {
      "matches": [
        "http://*/*",
        "https://*/*"
      ],
      "run_at": "document_start",
      "js": [
        "includes/content.js"
      ],
      "all_frames": true
    }
  ],
  "content_security_policy": {
    "extension_pages": "default-src 'self'; connect-src https://api.igorware.com; font-src 'none'; img-src 'self'; media-src 'none'; object-src 'none'; style-src 'unsafe-inline'"
  },
  "permissions": [
    "scripting",
    "storage",
    "tabs"
  ],
  "host_permissions": [
    "http://*/*",
    "https://*/*"
  ]
}