Examine source code of GitHub Tab Render Size

{
  "manifest_version": 2,
  "name": "GitHub tab render size",
  "version": "1.1resigned1",
  "description": "Adds a red border to all webpages matching mozilla.org.",
  "icons": {
    "16": "assets/icon16.png",
    "32": "assets/icon32.png",
    "48": "assets/icon48.png",
    "96": "assets/icon96.png",
    "128": "assets/icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.github.com/*"
      ],
      "js": [
        "github-tab-render-size.user.js"
      ]
    }
  ],
  "web_accessible_resources": [
    "spotify-ad-blocker_32x32.png"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{ab303118-bcd2-45b3-8de0-241517f11729}"
    }
  }
}