Examine source code of Shadow Trees

{
  "theme": {
    "images": {
      "theme_frame": "Trees_Header.jpg"
    },
    "colors": {
      "frame": "#cfc4c4",
      "tab_background_text": "#70bf7f"
    }
  },
  "version": "2.0",
  "name": "Shadow Trees",
  "manifest_version": 2,
  "description": "Shadowy trees against a black background"
}