Examine source code of gists-up

{
  "name": "gists-up",
  "version": "0.5.0",
  "manifest_version": 2,
  "description": "Browser add-on adds a set of useful features to Github Gists",
  "icons": {
    "128": "icons/icon128.png"
  },
  "applications": {
    "gecko": {
      "id": "@gistup",
      "strict_min_version": "57.0"
    }
  },
  "permissions": [
    "activeTab",
    "https://gist.github.com/*",
    "storage"
  ],
  "content_scripts": [
    {
      "run_at": "document_start",
      "matches": [
        "https://gist.github.com/*"
      ],
      "css": [
        "css/inject.css"
      ],
      "js": [
        "js/inject/index.js"
      ]
    }
  ],
  "options_ui": {
    "page": "html/options.html",
    "browser_style": false,
    "open_in_tab": false
  }
}