body {
  background-color: #000;
  overflow: hidden;
  position: relative;
}

body::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background-image: url('https://xn--xu0a.cn/favicon.ico');
  animation: float 10s ease-in-out infinite;
}

@keyframes float {
  0% {
    transform: translateX(-100%);
  }
  50% {
    transform: translateX(100%);
  }
  100% {
    transform: translateX(-100%);
  }
}