.square-waiting {
  width: 40px;
  height: 10px;
  position: relative;
  margin: 0px;
  box-sizing: border-box;
}

.square-waiting-box {
  top: 3px;
  position: absolute;
  width: 20%;
  height: 100%;
  animation: square-waiting-box 1s linear infinite;
}

.square-waiting-box:nth-child(1) {
  animation-delay: 0.25s;
}

.square-waiting-box:nth-child(2) {
  animation-delay: 0.50s;
  left: 25%;
}

.square-waiting-box:nth-child(3) {
  animation-delay: 0.75s;
  left: 50%;
}

.square-waiting-box:nth-child(4) {
  animation-delay: 1s;
  left: 75%;
}

@keyframes square-waiting-box {
  from {
    background: #aaaaaa;
  }
}