html, body {
  height: 100%;
  margin: 0;
}

.fullscreen-container {
  position: relative;
  width: 100%;
  height: 100vh; /* pun ekran */
  display: flex;
  justify-content: center;
  align-items: center;
}
@keyframes moveAround {
  0%   { transform: translate(0, 0); }
  25%  { transform: translate(50px, -50px); }
  50%  { transform: translate(0, -40px); }
  75%  { transform: translate(-50px, -50px); }
  100% { transform: translate(0, 0); }
}

.moving-box {
  animation: moveAround 5s infinite ease-in-out;
}