Examine source code of GRAY_AREA

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "GARY'S XPI",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-005-f5f3cf677b1f132c75ddc7bd319dd1fc.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(96, 96, 96)",
      "toolbar_text": "rgb(227, 227, 227)",
      "frame": "rgb(102, 102, 102)",
      "tab_background_text": "rgb(212, 212, 212)",
      "toolbar_field": "rgb(114, 114, 114)",
      "toolbar_field_text": "rgb(173, 173, 173)",
      "tab_line": "rgb(187, 187, 187)",
      "popup": "rgb(151, 151, 151)",
      "popup_text": "rgb(247, 247, 247)",
      "tab_loading": "rgb(187, 187, 187)"
    }
  }
}