Shimmering skeleton placeholders while loading

/* Loading placeholder; add aria-hidden="true" to the markup element. */
.skeleton {
  --skeleton-base: #e4e7ec;
  --skeleton-shine: #f2f4f7;
  display: block;
  border-radius: 0.5rem;
  background-color: var(--skeleton-base);
  background-image: linear-gradient(90deg, transparent, var(--skeleton-shine), transparent);
  background-size: 200% 100%;
  background-repeat: no-repeat;
  animation: shimmer 1.4s ease-in-out infinite;
}

.skeleton--text {
  height: 0.9rem;
  margin-block: 0.5rem;
}

.skeleton--avatar {
  width: 3rem;
  height: 3rem;
  border-radius: 50%;
}

@keyframes shimmer {
  from { background-position: 200% 0; }
  to { background-position: -200% 0; }
}

/* Users who prefer reduced motion get a static placeholder. */
@media (prefers-reduced-motion: reduce) {
  .skeleton {
    animation: none;
  }
}