Examine source code of Kitty's Halloween

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#3b3b3b",
      "tab_background_text": "#fffcab"
    }
  },
  "version": "2.0",
  "name": "Kitty's Halloween",
  "manifest_version": 2,
  "description": "Happy Halloween!\n\npumpkin, spider, web, orange cat, jack-o-lantern"
}