Examine source code of Tunnel-like pathway

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Tunnel-like pathway",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(73, 53, 53, 0.44)",
      "toolbar_text": "rgb(238, 233, 233)",
      "frame": "rgb(157, 183, 190)",
      "tab_background_text": "rgb(245, 247, 242)",
      "toolbar_field": "rgb(255, 255, 255)",
      "toolbar_field_text": "rgb(0, 0, 9)",
      "tab_line": "rgb(11, 1, 0)",
      "popup": "rgb(255, 255, 255)",
      "popup_text": "rgb(0, 1, 12)",
      "tab_loading": "rgb(11, 1, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1a23dd02-4210-4db5-8f73-b8ea61a94a30}"
    }
  }
}