Examine source code of Toggle Colors

{
  "manifest_version": 3,
  "name": "Toggle Colors",
  "version": "1.0",
  "description": "Simple button to toggle custom colors (aka. high contrast / overrideDocumentColors / browser.display.document_color_use)",
  "browser_specific_settings": {
    "gecko": {
      "id": "toggle-colors@yhoko.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "48": "icon-48.png",
    "96": "icon-96.png"
  },
  "permissions": [
    "browserSettings"
  ],
  "action": {
    "default_title": "Toggle Colors"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}