Examine source code of Cicles - Circulos

{
  "theme": {
    "images": {
      "theme_frame": "1.jpg"
    },
    "colors": {
      "frame": "#c2c2c2",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Cicles - Circulos",
  "manifest_version": 2,
  "description": "Many circles for your Firefox, modern and attractive. - Muchos circulos para tu Firefox, modernos y atractivos."
}