Examine source code of halloween skull

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "halloween",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png",
        "images/1.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top",
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat",
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(244, 136, 0)",
      "toolbar_text": "rgb(25, 20, 20)",
      "frame": "rgb(169, 87, 13)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(23, 22, 22)",
      "toolbar_field_text": "rgb(251, 0, 0)",
      "tab_line": "rgb(0, 0, 0)",
      "popup": "rgb(207, 47, 44)",
      "popup_text": "rgb(0, 0, 0)",
      "tab_loading": "rgb(0, 0, 0)"
    }
  }
}