Examine source code of Dulce M.

{
  "theme": {
    "images": {
      "theme_frame": "Mozilla.jpg"
    },
    "colors": {
      "frame": "#b0a2a2",
      "tab_background_text": "#8c8585"
    }
  },
  "version": "2.0",
  "name": "Dulce M.",
  "manifest_version": 2
}