.box {
  height: 5cm;
  width: 5cm;
  border: 5px solid #ffa600;
  box-shadow: inset 0 0 0 #ffa600;
  animation: load 2s ease-in-out infinite;
}

@keyframes load {
  0% {
    box-shadow: inset -5cm -2.5cm 0 #ffa600;
  }

  25% {
    box-shadow: inset 5cm -2.5cm 0 #ffa600;
  }

  25.01% {
    box-shadow: inset 2.5cm -5cm 0 #ffa600;
  }

  50% {
    box-shadow: inset 2.5cm 5cm 0 #ffa600;
  }

  50.01% {
    box-shadow: inset 5cm 2.5cm 0 #ffa600;
  }

  75% {
    box-shadow: inset -5cm 2.5cm 0 #ffa600;
  }

  75.01% {
    box-shadow: inset -2.5cm 5cm 0 #ffa600;
  }

  100% {
    box-shadow: inset -2.5cm -5cm 0 #ffa600;
  }
}