Examine source code of Zettel.cards

{
  "manifest_version": 2,
  "name": "Zettel.cards",
  "version": "1.3.5",
  "permissions": [
    "https://db.zettel.cards/*",
    "storage",
    "contextMenus",
    "tabs",
    "activeTab"
  ],
  "background": {
    "scripts": [
      "public/build/background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_popup": "public/browser_action.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "public/build/injection.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{0a8ae694-ed38-4637-b61a-7fb2f7ccd6b4}"
    }
  }
}