Examine source code of Twilight Maze

{
  "manifest_version": 2,
  "version": "2.5",
  "name": "Twilight Maze",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(0, 13, 99, 0)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(0, 13, 99)",
      "tab_background_text": "rgb(215, 217, 239)",
      "toolbar_field": "rgb(5, 19, 126)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgba(154, 177, 255, 0.41)",
      "popup": "rgb(0, 13, 99)",
      "popup_text": "rgb(215, 219, 239)",
      "popup_border": "rgb(0, 13, 99)",
      "popup_highlight": "rgba(154, 185, 255, 0.53)",
      "tab_loading": "rgba(154, 177, 255, 0.41)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{88874558-cde2-4cd8-b707-785c2154f3c7}"
    }
  }
}