Examine source code of DarkUbuntu

{
  "theme": {
    "images": {
      "theme_frame": "ubuntu_header_new.jpg"
    },
    "colors": {
      "frame": "#756a6a",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "DarkUbuntu",
  "manifest_version": 2,
  "description": "A dark persona for Ubuntu fans"
}