Examine source code of US Flag Stars

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "US Flag Stars",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "right top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(26, 29, 47)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(26, 29, 47)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(34, 38, 56)",
      "toolbar_field_text": "rgb(255, 255, 255)",
      "tab_line": "rgb(78, 112, 172)",
      "popup": "rgb(34, 38, 56)",
      "popup_text": "rgb(255, 255, 255)",
      "button_background_active": "rgb(26, 29, 47)",
      "button_background_hover": "rgb(34, 38, 56)",
      "icons": "rgb(255, 255, 255)",
      "popup_border": "rgb(179, 37, 55)",
      "popup_highlight": "rgb(177, 34, 52)",
      "sidebar_border": "rgb(34, 38, 56)",
      "sidebar_highlight_text": "rgb(174, 34, 52)",
      "sidebar_highlight": "rgb(177, 34, 52)",
      "sidebar_text": "rgb(255, 255, 255)",
      "tab_loading": "rgb(78, 112, 172)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{6ac9d0d0-7258-4759-a573-b629385e420b}"
    }
  }
}