Examine source code of Marseille Firefox

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "rgba(229,230,232,1)",
      "tab_background_text": "#fcf9f9"
    }
  },
  "version": "2.0",
  "name": "Marseille Firefox",
  "manifest_version": 2,
  "description": "Marseille colors of Firefox !\nfor the pleasure of sharing\n\nMarseille, 2,600 years of history around the Old Port, along the Mediterranean. European Capital of Culture in 2013"
}