Examine source code of blue signs three

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "blue signs three",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(225, 234, 239, 0)",
      "toolbar_text": "rgb(252, 249, 250)",
      "frame": "rgb(142, 179, 201)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(255, 255, 255)",
      "toolbar_field_text": "rgb(49, 51, 89)",
      "tab_line": "rgb(61, 137, 244)",
      "popup": "rgb(255, 255, 255)",
      "popup_text": "rgb(8, 8, 8)",
      "tab_loading": "rgb(61, 137, 244)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5122e156-8a4a-473c-8bcf-4d5fd24cbc63}"
    }
  }
}