Indeterminate progress indicator a la Windows XP boot

index.css

.bar {
  background-color: white;
  width: 200px;
  padding: 4px;
  border-radius: 4px;
  border: 2px solid;
  overflow: hidden;

  height: 20px;
}

.bar > .indicator {
  animation-duration: 2s;
  animation-name: loop;
  animation-iteration-count: infinite;
  animation-timing-function: linear;
}

@keyframes loop {
  from {
    transform: translate(-100%);
  }

  to {
    transform: translate(100%);
  }
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
  box-sizing: border-box;
  padding: 50px;
  background: radial-gradient(hsl(30, 80%, 80%), hsl(210, 50%, 70%)) no-repeat
    center;
}

html,
body {
  height: 100%;
}

index.html

<div class="bar">
  <div class="indicator">
    👾👾👾
  </div>
</div>