Examine source code of Cocktail Gradient

{
  "theme": {
    "images": {
      "theme_frame": "Gradient5-Header.jpg"
    },
    "colors": {
      "frame": "#0d0d0d",
      "tab_background_text": "#b0aeae"
    }
  },
  "version": "2.0",
  "name": "Cocktail Gradient",
  "manifest_version": 2,
  "description": "Warm Tropical gradient Bring some warmth to your firefox."
}