Examine source code of Green with Cross

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Green with Cross",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "no-repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(249, 249, 251)",
      "toolbar_text": "rgb(60, 60, 60)",
      "frame": "rgb(0, 98, 75)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(240, 240, 240)",
      "toolbar_field_text": "rgb(55, 55, 55)",
      "tab_line": "rgba(255, 255, 255, 0)",
      "popup": "rgb(255, 255, 255)",
      "popup_text": "rgb(0, 0, 0)",
      "popup_highlight": "rgb(0, 98, 75)",
      "toolbar_bottom_separator": "rgb(249, 249, 251)",
      "toolbar_field_border_focus": "rgb(0, 98, 75)",
      "toolbar_field_focus": "rgb(255, 255, 255)",
      "toolbar_top_separator": "rgba(249, 249, 251, 0)",
      "tab_loading": "rgba(255, 255, 255, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{34751f36-2b0f-4eab-9aac-e15d405275d5}"
    }
  }
}