Examine source code of green cityscape

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "green cityscape",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center top"
      ],
      "additional_backgrounds_tiling": [
        "repeat-x"
      ]
    },
    "colors": {
      "toolbar": "rgba(0, 0, 0, 0.59)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(0, 0, 0)",
      "toolbar_field_text": "rgb(65, 255, 33)",
      "tab_line": "rgb(65, 255, 33)",
      "popup": "rgb(0, 0, 0)",
      "popup_text": "rgb(65, 255, 33)",
      "tab_loading": "rgb(65, 255, 33)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f47b8f11-e22f-4c4e-87e7-7ea535a6104d}"
    }
  }
}