Examine source code of Firefox Blue Moons

{
  "theme": {
    "images": {
      "theme_frame": "firefoxnight.jpg"
    },
    "colors": {
      "frame": "#74b3db",
      "tab_background_text": "#74b3db"
    }
  },
  "version": "2.0",
  "name": "Firefox Blue Moons",
  "manifest_version": 2,
  "description": "Two blue moons surrounded by their blue Firefoxes in a night-sky landscape."
}