Examine source code of Cozy Rain Goddess

{
  "manifest_version": 2,
  "version": "3",
  "name": "v3",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right bottom"
      ],
      "additional_backgrounds_tiling": [
        "no-repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(225, 234, 239, 0)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(32, 39, 59)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(65, 69, 78)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgba(255, 255, 255, 0.12)",
      "popup": "rgb(65, 69, 78)",
      "popup_text": "rgb(255, 255, 255)",
      "tab_loading": "rgba(255, 255, 255, 0.12)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{585a05d3-7611-4539-8d82-1595a0f4cfe2}"
    }
  }
}