Examine source code of coupo4u

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Rock Formation on Sea",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(22, 72, 75, 0.8)",
      "toolbar_text": "rgb(242, 247, 247)",
      "frame": "rgb(22, 54, 75)",
      "tab_background_text": "rgb(246, 248, 251)",
      "toolbar_field": "rgba(0, 0, 0, 0.2)",
      "toolbar_field_text": "rgb(238, 227, 229)",
      "tab_line": "rgb(28, 171, 176)",
      "popup": "rgb(12, 12, 12)",
      "popup_text": "rgb(240, 243, 243)",
      "tab_loading": "rgb(28, 171, 176)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{66058741-ddb7-4bb7-8dd9-a589aeb6a380}"
    }
  }
}