Examine source code of Cat City

{
  "name": "Cat City",
  "manifest_version": 2,
  "version": "2.0",
  "theme": {
    "images": {
      "theme_frame": "cats.jpg"
    },
    "colors": {
      "frame": "#227db5",
      "tab_background_text": "#e5f5ff",
      "toolbar": "rgba(255, 255, 255, 0.07)",
      "toolbar_field": "rgba(0, 0, 0, 0)",
      "toolbar_field_text": "rgba(255, 255, 255, 1)"
    }
  }
}