body {
  background-color: #106;
  background-image:
    radial-gradient(at 0 0, #f70, transparent 40%),
    radial-gradient(at 0 40%, #0df, transparent 40%),
    radial-gradient(at 40% 60%, #01f, transparent 80%),
    radial-gradient(at 0 100%, #faa, transparent 50%);
  background-attachment: fixed;
}