Examine source code of Pixel City - Smokestack

{
  "theme": {
    "images": {
      "theme_frame": "firefoxstack.jpg"
    },
    "colors": {
      "frame": "#cf8c06",
      "tab_background_text": "#363635"
    }
  },
  "version": "2.0",
  "name": "Pixel City - Smokestack",
  "manifest_version": 2,
  "description": "A pixelized smokestack in a city with an orange sky."
}