Examine source code of Greyed Toolbar

{
  "manifest_version": 2,
  "version": "2.0",
  "name": "2.0",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-026-829b05416f823e170310e7c826ad1bec.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(31, 34, 34)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(8, 8, 8)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(0, 0, 0)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgba(255, 255, 255, 0)",
      "popup": "rgb(31, 34, 34)",
      "popup_text": "rgb(255, 255, 255)",
      "tab_loading": "rgba(255, 255, 255, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{82d64de2-b802-4cc4-b8cf-a3f79ed5284f}"
    }
  }
}