Examine source code of Companion Cube Nighttime

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "portal companion cube v2",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(29, 29, 30, 0.47)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(142, 179, 201)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(45, 43, 47)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(212, 0, 184)",
      "popup": "rgb(0, 0, 0)",
      "popup_text": "rgb(98, 102, 183)",
      "toolbar_top_separator": "rgb(212, 0, 184)",
      "tab_loading": "rgb(212, 0, 184)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{cad7a94b-f838-46a9-a878-be28f7fcf782}"
    }
  }
}