Examine source code of Old School Pencilcase

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Old School Pencilcase",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/bg-005-f5f3cf677b1f132c75ddc7bd319dd1fc.svg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(40, 71, 78)",
      "toolbar_text": "rgb(236, 234, 191)",
      "frame": "rgb(40, 71, 78)",
      "tab_background_text": "rgb(236, 234, 191)",
      "toolbar_field": "rgb(215, 214, 188)",
      "toolbar_field_text": "rgb(40, 71, 78)",
      "tab_line": "rgb(236, 234, 191)",
      "popup": "rgb(40, 71, 78)",
      "popup_text": "rgb(236, 234, 191)",
      "button_background_active": "rgb(236, 234, 191)",
      "frame_inactive": "rgb(236, 234, 191)",
      "icons": "rgb(236, 234, 191)",
      "ntp_text": "rgb(236, 234, 191)",
      "tab_loading": "rgb(236, 234, 191)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{13cfafb8-a661-4deb-a891-d1aede5053e2}"
    }
  }
}