Examine source code of Firefox_nature

{
  "theme": {
    "images": {
      "theme_frame": "Immagine1.jpeg"
    },
    "colors": {
      "frame": "#030303",
      "tab_background_text": "#030303"
    }
  },
  "version": "2.0",
  "name": "Firefox_nature",
  "manifest_version": 2,
  "description": "Nature..."
}