Examine source code of Brass Fractal

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Brass Fractal",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgba(38, 27, 0, 0.63)",
      "toolbar_text": "rgb(255, 186, 0)",
      "frame": "rgb(38, 27, 0)",
      "tab_background_text": "rgb(255, 208, 84)",
      "toolbar_field": "rgb(38, 27, 0)",
      "toolbar_field_text": "rgb(255, 186, 0)",
      "tab_line": "rgb(255, 186, 0)",
      "popup": "rgb(38, 27, 0)",
      "popup_text": "rgb(255, 186, 0)",
      "popup_border": "rgba(255, 186, 0, 0)",
      "popup_highlight": "rgb(255, 186, 0)",
      "sidebar_border": "rgba(255, 186, 0, 0)",
      "sidebar_text": "rgb(255, 186, 0)",
      "tab_loading": "rgb(255, 186, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{561d88f8-5c66-45fc-ac89-4b3eee0e96ad}"
    }
  }
}