Examine source code of ArrowsMod

{
  "manifest_version": 2,
  "name": "ArrowsMod",
  "version": "1.2.0",
  "description": "mod #1 for logic arrows",
  "author": "Gulg, lolpopgames, lwjenni",
  "browser_action": {
    "default_icon": "icon128.png",
    "default_title": "ArrowsMod"
  },
  "icons": {
    "16": "icon16.png",
    "32": "icon32.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://*.logic-arrows.io/*"
      ],
      "run_at": "document_start",
      "js": [
        "mod.bundle.js"
      ],
      "css": [
        "mod.bundle.css"
      ],
      "all_frames": true
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "arrowsmod@gmail.com"
    }
  }
}