Examine source code of Minecraft Copper

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Minecraft Copper",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(249, 193, 151)",
      "toolbar_text": "rgb(255, 96, 0)",
      "frame": "rgb(201, 164, 142)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(255, 255, 255)",
      "toolbar_field_text": "rgb(0, 0, 0)",
      "tab_line": "rgb(255, 111, 0)",
      "popup": "rgb(255, 226, 204)",
      "popup_text": "rgb(183, 98, 98)",
      "tab_loading": "rgb(255, 111, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{7adad323-c5d4-4b60-a512-43031efde05c}"
    }
  }
}