body:before{
  content: "Oh no!\A\AThis page is red, it should not have been.\A\APlease enable JavaScript to use this page.";
  white-space: pre-wrap;

  color: white;
  font-family: sans-serif;
  font-size: 1rem;
  font-weight: bold;
  text-align: center;

  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;

  background: rgba(255,0,0,0.85);

  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 99999;
}