Examine source code of Gridded Matte

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Gridded Matte",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-005-f5f3cf677b1f132c75ddc7bd319dd1fc.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(14, 14, 14)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(188, 188, 188)",
      "toolbar_field": "rgb(27, 27, 27)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgba(106, 106, 106, 0.47)",
      "popup": "rgb(14, 14, 14)",
      "popup_text": "rgb(255, 255, 255)",
      "popup_border": "rgba(106, 106, 106, 0.47)",
      "popup_highlight_text": "rgb(255, 255, 255)",
      "tab_loading": "rgba(106, 106, 106, 0.47)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{80588c56-d382-45a6-8dd9-20ad5a5bbf7d}"
    }
  }
}