userContent.css prank

@-moz-document regexp("http.*"), url-prefix(about:) {
  @keyframes rotation {
    from {
      transform: rotate(0turn);
    }

    to {
      transform: rotate(1turn);
    }
  }

  body, #newtab-window {
    animation-duration: 10800s;
    animation-name: rotation;
    animation-iteration-count: infinite;
    animation-timing-function: linear;
  }
}