Examine source code of Blue Planet 2

{
  "theme": {
    "images": {
      "theme_frame": "the-sun-blue_3000x200.jpg"
    },
    "colors": {
      "frame": "#1025ad",
      "tab_background_text": "#fcfcfc"
    }
  },
  "version": "2.0",
  "name": "Blue Planet 2",
  "manifest_version": 2
}