Examine source code of Nightingale

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Nightingale",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "no-repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(0, 0, 0, 0.64)",
      "toolbar_text": "rgb(105, 9, 183)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(38, 0, 255)",
      "toolbar_field": "rgba(0, 77, 93, 0.36)",
      "toolbar_field_text": "rgb(0, 0, 0)",
      "tab_line": "rgb(90, 74, 52)",
      "popup": "rgb(0, 0, 0)",
      "popup_text": "rgb(0, 230, 255)",
      "tab_loading": "rgb(90, 74, 52)"
    }
  }
}