Examine source code of Pentagram

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Pentagram",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(255, 213, 194, 0.31)",
      "toolbar_text": "rgb(253, 253, 253)",
      "frame": "rgb(189, 114, 39)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(255, 255, 255)",
      "toolbar_field_text": "rgb(0, 0, 0)",
      "tab_line": "rgb(141, 248, 112)",
      "popup": "rgb(217, 217, 217)",
      "popup_text": "rgb(11, 11, 11)",
      "tab_loading": "rgb(141, 248, 112)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{f8fed883-10fa-47ec-bca1-4545c1215cd6}"
    }
  }
}