Examine source code of Kelp forest

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Kelp forest",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg",
        "images/1.jpg",
        "images/2.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "left center",
        "center center",
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "repeat",
        "no-repeat",
        "no-repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(13, 60, 34, 0.5)",
      "toolbar_text": "rgb(42, 212, 130)",
      "frame": "rgb(11, 86, 43)",
      "tab_background_text": "rgb(16, 247, 134)",
      "toolbar_field": "rgba(10, 47, 36, 0.3)",
      "toolbar_field_text": "rgb(55, 247, 155)",
      "tab_line": "rgba(61, 214, 173, 0.75)",
      "popup": "rgba(8, 35, 20, 0.98)",
      "popup_text": "rgb(39, 168, 106)",
      "tab_loading": "rgba(61, 214, 173, 0.75)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{aed03f6c-7e6f-4587-86aa-d35d168a15c6}"
    }
  }
}