Examine source code of Numix Blue

{
  "manifest_version": 2,
  "name": "Numix Blue",
  "description": "Numix background with some blue accents.",
  "version": "1.2",
  "author": "Dillinger",
  "homepage_url": "https://addons.thunderbird.net/en-US/thunderbird/user/dillinger/themes",
  "theme": {
    "images": {
      "theme_frame": "numix-blue-header.png"
    },
    "colors": {
      "frame": "#2d2d2d",
      "tab_background_text": "#f9f9f9",
      "tab_line": "#42a5f5",
      "tab_loading": "#42a5f5"
    }
  },
  "applications": {
    "gecko": {
      "id": "numix-blue@dillinger",
      "strict_min_version": "60.0"
    }
  },
  "icons": {
    "32": "numix-blue-icon.png"
  }
}