Examine source code of Black Hold

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Black Hold",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "left center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(121, 184, 219, 0.1)",
      "toolbar_text": "rgb(0, 0, 0)",
      "frame": "rgb(142, 179, 201)",
      "tab_background_text": "rgb(118, 16, 190)",
      "toolbar_field": "rgba(2, 27, 39, 0.15)",
      "toolbar_field_text": "rgb(0, 0, 0)",
      "tab_line": "rgb(74, 74, 182)",
      "popup": "rgb(24, 2, 2)",
      "popup_text": "rgb(118, 16, 190)",
      "tab_loading": "rgb(74, 74, 182)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{e1210d5c-5756-4cbd-967c-2c020c9b8e82}"
    }
  }
}