Examine source code of Sky

{
  "manifest_version": 2,
  "version": "1.3",
  "name": "Sky with clouds",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center bottom"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(250, 250, 250, 0.9)",
      "toolbar_text": "rgba(0, 0, 0, 0.73)",
      "frame": "rgb(250, 250, 250)",
      "tab_background_text": "rgb(0, 0, 0)",
      "toolbar_field": "rgb(255, 255, 255)",
      "toolbar_field_text": "rgba(0, 0, 0, 0.8)",
      "tab_line": "rgb(237, 241, 244)",
      "popup": "rgb(255, 255, 255)",
      "popup_text": "rgba(0, 0, 0, 0.9)",
      "tab_loading": "rgb(237, 241, 244)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9c24d100-353f-499d-b26e-93ec29baff9c}"
    }
  }
}