Examine source code of FullHex

{
  "manifest_version": 3,
  "name": "FullHex",
  "version": "1.1.0",
  "description": "Removes the blank ad-space gutters on colonist.io and resizes the game board to fill the window. Not affiliated with colonist.io.",
  "icons": {
    "16": "icon-16.png",
    "32": "icon-32.png",
    "48": "icon-48.png",
    "128": "icon-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://colonist.io/*",
        "*://*.colonist.io/*"
      ],
      "css": [
        "content.css"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start",
      "all_frames": false
    }
  ],
  "web_accessible_resources": [
    {
      "resources": [
        "page.js"
      ],
      "matches": [
        "*://colonist.io/*",
        "*://*.colonist.io/*"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "fullhex@local",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  }
}