Stylish CSS for production domain.

stylish.css

@namespace url(http://www.w3.org/1999/xhtml);

@-moz-document domain("my-domain.com") {
  body {
      border-top: 2px solid orange;
  }

  body:before {
      background-color: orange;
      content: "PROD";
      left: -1px;
      padding: 1px;
      position: absolute;
      top: -2px;
  }
}