Heatmap

<!-- Heatmap (5×7 grid — fill cell classes from your data) -->
<div class="nuda-heatmap" role="img" aria-label="Activity heatmap">
  <span class="nuda-heatmap__cell is-low"  style="--d: 0s"></span>
  <span class="nuda-heatmap__cell is-mid"  style="--d: .04s"></span>
  <span class="nuda-heatmap__cell is-high" style="--d: .08s"></span>
  <span class="nuda-heatmap__cell is-empty" style="--d: .12s"></span>
  <!-- ...repeat for 35 cells, vary class by intensity (is-empty / is-low / is-mid / is-high) -->
</div>

/* Heatmap
   Activity grid (e.g. GitHub-style) with cells popping in then breathing.
   Customize: --hm-color, --hm-empty, --hm-cols */

.nuda-heatmap {
  --hm-color: #e4ff54;
  --hm-empty: rgba(255, 255, 255, 0.04);
  --hm-cols: 7;
  display: grid;
  grid-template-columns: repeat(var(--hm-cols), 1fr);
  gap: 3px;
  width: 100%;
  max-width: 220px;
  padding: 4px;
}

.nuda-heatmap__cell {
  aspect-ratio: 1;
  border-radius: 2px;
  background: var(--hm-empty);
  transform: scale(0.6);
  opacity: 0;
  animation:
    nuda-heatmap-pop 0.5s cubic-bezier(0.4, 0, 0.2, 1) var(--d, 0s) forwards,
    nuda-heatmap-loop 4s ease-in-out var(--d, 0s) infinite;
}

.nuda-heatmap__cell.is-low  { background: rgba(228, 255, 84, 0.25); }
.nuda-heatmap__cell.is-mid  { background: rgba(228, 255, 84, 0.55); }
.nuda-heatmap__cell.is-high {
  background: var(--hm-color);
  box-shadow: 0 0 4px rgba(228, 255, 84, 0.4);
}

@keyframes nuda-heatmap-pop {
  to { transform: scale(1); opacity: 1; }
}

@keyframes nuda-heatmap-loop {
  0%, 100% { filter: brightness(1); }
  50%      { filter: brightness(1.3); }
}

@media (prefers-reduced-motion: reduce) {
  .nuda-heatmap__cell { animation: none; transform: scale(1); opacity: 1; }
}