Examine source code of Clouds in Space

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#6d8fc9",
      "tab_background_text": "#0a174d"
    }
  },
  "version": "2.0",
  "name": "Clouds in Space",
  "manifest_version": 2,
  "description": "Using a gradient as a background, added stars, planets, birds and clouds using brushes compatible with PhotoShop Elements."
}