Examine source code of Nebulae Horsehead

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Nebulae",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "left bottom"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(219, 189, 117)",
      "toolbar_text": "rgb(27, 55, 23)",
      "frame": "rgb(142, 179, 201)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(255, 255, 255)",
      "toolbar_field_text": "rgb(44, 46, 74)",
      "tab_line": "rgb(248, 112, 140)",
      "popup": "rgb(255, 255, 255)",
      "popup_text": "rgb(37, 45, 190)",
      "tab_loading": "rgb(248, 112, 140)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{d071e7d8-7021-4a20-9cfb-6f2df2f1393e}"
    }
  }
}