style.css

/* Set background color and 3D effect */
body {
  background: linear-gradient(to right top, #ff9800, #ffc107, #ffeb3b, #cddc39, #8bc34a);
  perspective: 50rem;
  transform-style: preserve-3d;
}

/* Add GIF to upper right corner */
#sad-gif {
  position: fixed;
  top: 0;
  right: 0;
  height: 5rem;
  width: 5rem;
  transform: translateZ(3rem) rotateY(-180deg);
}