Examine source code of Grey Night

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Grey Night",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-011-d53e0d0d1538ed554a90e056a2f04eca.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(138, 138, 140)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(67, 69, 70)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(67, 69, 70)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(255, 255, 255)",
      "popup": "rgb(69, 69, 69)",
      "popup_text": "rgb(255, 255, 255)",
      "button_background_hover": "rgb(255, 255, 255)",
      "icons_attention": "rgb(255, 255, 255)",
      "tab_selected": "rgb(206, 202, 195)",
      "tab_text": "rgb(6, 6, 6)",
      "tab_loading": "rgb(255, 255, 255)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{abfc8c81-75e1-422d-852a-5b77206668f0}"
    }
  }
}