Examine source code of Save Trees

{
  "theme": {
    "images": {
      "theme_frame": "Trees.png"
    },
    "colors": {
      "frame": "#313d2b",
      "tab_background_text": "#d9f2e4"
    }
  },
  "version": "2.0",
  "name": "Save Trees",
  "manifest_version": 2
}