body {
  background: url("brainyellow.png") repeat;
  animation: scrolling 5s linear infinite;
}
@keyframes scrolling {
  from {
    background-position: 0 0;
  }
  to {
    background-position: -900px 900px;
  }
}

h1, p {
  color: powderblue;
  text-align: center;
}

img {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  max-width: 100%;
  height: auto;
}