Examine source code of Never Again

{
  "manifest_version": 2,
  "name": "Never Again",
  "version": "1.6",
  "description": "Reminds you who the climate criminals are, starting with Siemens.",
  "icons": {
    "32": "icons/na-48x48-optimized.svg",
    "48": "icons/na-48x48-optimized.svg",
    "64": "icons/na-48x48-optimized.svg",
    "96": "icons/na-48x48-optimized.svg"
  },
  "permissions": [
    "http://*/*",
    "https://*/*"
  ],
  "content_scripts": [
    {
      "exclude_matches": [
        "*://*.mattermost.com/*"
      ],
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "neverAgain.js"
      ],
      "css": [
        "neverAgain.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{afb3a50a-befa-4036-806a-fe640bd2e082}"
    }
  }
}