Examine source code of Sparkle

{
  "manifest_version": 3,
  "name": "Sparkle",
  "version": "1.5.1",
  "description": "Learn Chinese while you browse. Sparkle quietly swaps a few English words on every page for the HSK vocabulary you are studying.",
  "default_locale": "en",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "storage",
    "alarms"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "exclude_matches": [
        "*://sparklechinese.com/*",
        "*://*.sparklechinese.com/*",
        "*://sparkle-ashy.vercel.app/*",
        "*://*.sparkle-ashy.vercel.app/*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_idle",
      "all_frames": false,
      "match_about_blank": false
    }
  ],
  "action": {
    "default_title": "Sparkle",
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    }
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": true
  },
  "content_security_policy": {
    "extension_pages": "script-src 'self'; object-src 'self'; connect-src 'self'"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "type": "module"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "sparkle@sparkle.study",
      "strict_min_version": "128.0"
    },
    "gecko_android": {
      "strict_min_version": "128.0"
    }
  },
  "optional_host_permissions": [
    "<all_urls>"
  ]
}