Examine source code of Mecabricks shortcuts box

{
  "manifest_version": 2,
  "name": "Mecabricks shortcuts toolbox",
  "version": "0.31",
  "description": "Add shortcuts to usefull bricks on toolbar",
  "permissions": [
    "*://mecabricks.com/*/workshop*",
    "*://www.mecabricks.com/*/workshop*",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://mecabricks.com/*/workshop*",
        "*://www.mecabricks.com/*/workshop*"
      ],
      "js": [
        "jquery-3.5.1.slim.min.js",
        "mb-dom.js"
      ],
      "css": [
        "mb.css"
      ],
      "run_at": "document_end"
    }
  ],
  "options_ui": {
    "page": "options/options.html"
  },
  "web_accessible_resources": [
    "img/*.png"
  ],
  "icons": {
    "16": "img/16.png",
    "32": "img/32.png",
    "64": "img/64.png"
  },
  "browser_action": {
    "default_title": "MB addon Options",
    "default_popup": "options/options.html"
  }
}