<div class="sk-classic">
  <div class="sk-bar" style="width: 70%"></div>
  <div class="sk-bar" style="width: 90%"></div>
  <div class="sk-bar" style="width: 60%"></div>
</div>

.sk-classic {
  width: 220px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}
.sk-bar {
  height: 12px;
  border-radius: 6px;
  background: linear-gradient(90deg, #1f1f28 0%, #2a2a36 50%, #1f1f28 100%);
  background-size: 200% 100%;
  animation: skClassic 1.4s linear infinite;
}
@keyframes skClassic {
  0% {
    background-position: 200% 0;
  }
  100% {
    background-position: -200% 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  .sk-classic,
  .sk-classic * {
    animation: none !important;
  }
}