Examine source code of Blue-Green crystal cave

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Green crystal cave",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(16, 46, 53)",
      "toolbar_text": "rgb(204, 255, 255)",
      "frame": "rgb(22, 21, 19)",
      "tab_background_text": "rgb(207, 255, 239)",
      "toolbar_field": "rgb(8, 32, 38)",
      "toolbar_field_text": "rgb(204, 255, 255)",
      "tab_line": "rgb(47, 185, 174)",
      "popup": "rgb(8, 32, 38)",
      "popup_text": "rgb(204, 255, 255)",
      "button_background_active": "rgb(134, 193, 192)",
      "button_background_hover": "rgb(62, 189, 184)",
      "tab_loading": "rgb(47, 185, 174)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b772a412-a993-4383-8ded-c2d2cbb4797f}"
    }
  }
}