Examine source code of Thoughtful B&W

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Thoughtful",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "left center"
      ],
      "additional_backgrounds_tiling": [
        "no-repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(81, 81, 81)",
      "toolbar_text": "rgb(193, 193, 193)",
      "frame": "rgb(60, 61, 62)",
      "tab_background_text": "rgb(165, 161, 146)",
      "toolbar_field": "rgb(27, 34, 44)",
      "toolbar_field_text": "rgb(244, 240, 230)",
      "tab_line": "rgb(77, 97, 227)",
      "popup": "rgb(52, 52, 51)",
      "popup_text": "rgb(185, 142, 0)",
      "tab_loading": "rgb(77, 97, 227)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{75bdf4bb-5dac-4ea9-aa78-e0f39079b6b4}"
    }
  }
}