Voice Activity Meter

<div class="nuda-vmeter">
  <!-- Repeat 16 cells. Add .is-on up to current level, .is-hot for >=6 -->
  <span class="nuda-vmeter__cell is-on"></span>
  <span class="nuda-vmeter__cell is-on"></span>
  <!-- ... -->
  <span class="nuda-vmeter__cell is-on is-hot"></span>
  <span class="nuda-vmeter__cell"></span>
</div>

.nuda-vmeter {
  display: inline-flex;
  align-items: center;
  gap: 2px;
  padding: 8px 12px;
  background: rgba(0,0,0,.4);
  border-radius: 8px;
}

.nuda-vmeter__cell {
  width: 3px;
  height: 16px;
  background: rgba(255,255,255,.08);
  border-radius: 1px;
  transition: background .15s;
  animation: _vmeterPulse 1.2s ease-in-out infinite;
}

.nuda-vmeter__cell.is-on {
  background: #6ee7b7;
}

.nuda-vmeter__cell.is-hot.is-on {
  background: #ffb45e;
}

.nuda-vmeter__cell:not(.is-on) {
  animation: none;
}

@keyframes _vmeterPulse {
  0%,100% {
    opacity: .6;
    transform: scaleY(.6);
  }
  50% {
    opacity: 1;
    transform: scaleY(1);
  }
}

@media (prefers-reduced-motion:reduce) {
  .nuda-vmeter__cell {
    animation: none;
  }
}