Examine source code of Sunset over cloud

{
  "theme": {
    "images": {
      "theme_frame": "sunsetovercloud.png"
    },
    "colors": {
      "frame": "#2d4a63",
      "tab_background_text": "#fafafa"
    }
  },
  "version": "2.0",
  "name": "Sunset over cloud",
  "manifest_version": 2,
  "description": "Sunset over a cloud with its ray illuminating an orange and cobalt sky"
}