Examine source code of das apartment

{
  "theme": {
    "images": {
      "theme_frame": "firefox-banner.jpg"
    },
    "colors": {
      "frame": "#080000",
      "tab_background_text": "#f9fbfc"
    }
  },
  "version": "2.0",
  "name": "das apartment",
  "manifest_version": 2,
  "description": "das apartment hamburg"
}