Examine source code of Goodbye Blue Sky

{
  "manifest_version": 2,
  "version": "1.2",
  "name": "Goodbye Blue Sky",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-011-d53e0d0d1538ed554a90e056a2f04eca.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(144, 164, 189)",
      "toolbar_text": "rgb(0, 0, 0)",
      "frame": "rgb(48, 83, 120)",
      "tab_background_text": "rgb(209, 217, 229)",
      "toolbar_field": "rgba(235, 240, 247, 0.38)",
      "toolbar_field_text": "rgb(15, 75, 127)",
      "tab_line": "rgb(144, 164, 189)",
      "popup": "rgb(229, 240, 244)",
      "popup_text": "rgb(0, 0, 0)",
      "button_background_active": "rgb(99, 122, 154)",
      "button_background_hover": "rgb(118, 142, 177)",
      "icons": "rgb(22, 44, 64)",
      "tab_selected": "rgb(144, 164, 189)",
      "tab_text": "rgb(0, 0, 0)",
      "toolbar_field_highlight": "rgb(91, 147, 104)",
      "toolbar_top_separator": "rgb(144, 164, 189)",
      "tab_loading": "rgb(144, 164, 189)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1a9201e8-3f03-44e0-81fd-012dcccd4904}"
    }
  }
}