Examine source code of Forest Drawing

{
  "manifest_version": 2,
  "version": "1.1",
  "name": "Forest Drawing",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right bottom"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(47, 88, 48)",
      "toolbar_text": "rgb(194, 214, 199)",
      "frame": "rgb(34, 53, 34)",
      "tab_background_text": "rgb(150, 185, 158)",
      "toolbar_field": "rgb(163, 194, 170)",
      "toolbar_field_text": "rgb(112, 56, 0)",
      "tab_line": "rgb(112, 56, 0)",
      "popup": "rgb(47, 88, 48)",
      "popup_text": "rgb(255, 255, 255)",
      "tab_loading": "rgb(112, 56, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{81559fd4-5498-4df5-865e-ba8d7de23339}"
    }
  }
}