Examine source code of Mystery Cave

{
  "manifest_version": 2,
  "version": "2.0",
  "name": "Mystery Cave",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "no-repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(152, 108, 76, 0.57)",
      "toolbar_field": "rgba(152, 108, 76, 0.51)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(255, 132, 0)",
      "popup": "rgb(89, 62, 46)",
      "popup_text": "rgb(245, 245, 245)",
      "tab_loading": "rgb(255, 132, 0)",
      "bookmark_text": "rgb(255, 255, 255)",
      "frame": "rgb(152, 108, 76)",
      "tab_background_text": "rgb(255, 255, 255)"
    }
  }
}