Expanding Step Panels

<ol class="nuda-st2-expand-panels">
  <li class="is-done">
    <div class="nuda-st2-expand-panels__head">
      <span class="nuda-st2-expand-panels__num">✓<span class="nuda-st2-expand-panels__sr"> completed</span></span>
      <span class="nuda-st2-expand-panels__title">Shipping address</span>
    </div>
  </li>
  <li class="is-active" aria-current="step">
    <div class="nuda-st2-expand-panels__head">
      <span class="nuda-st2-expand-panels__num">2</span>
      <span class="nuda-st2-expand-panels__title">Delivery method</span>
    </div>
    <div class="nuda-st2-expand-panels__body">
      <p>Choose how fast you want it there.</p>
      <button type="button">Continue</button>
    </div>
  </li>
  <li>
    <div class="nuda-st2-expand-panels__head">
      <span class="nuda-st2-expand-panels__num">3</span>
      <span class="nuda-st2-expand-panels__title">Payment</span>
    </div>
  </li>
</ol>

.nuda-st2-expand-panels {
  list-style: none;
  margin: 0;
  padding: 0;
  width: 100%;
  max-width: 300px;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.nuda-st2-expand-panels li {
  background: rgba(255,255,255,.02);
  border: 1px solid rgba(255,255,255,.07);
  border-radius: 12px;
  overflow: hidden;
}

.nuda-st2-expand-panels__head {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 12px 14px;
  min-height: 44px;
}

.nuda-st2-expand-panels__num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 24px;
  height: 24px;
  flex-shrink: 0;
  border-radius: 50%;
  background: rgba(255,255,255,.05);
  border: 1px solid rgba(255,255,255,.12);
  color: #a0a0a8;
  font-size: 11px;
  font-weight: 700;
  transition: background .3s,border-color .3s,color .3s;
}

.nuda-st2-expand-panels li.is-done .nuda-st2-expand-panels__num {
  background: #e4ff54;
  border-color: #e4ff54;
  color: #09090b;
}

.nuda-st2-expand-panels li.is-active .nuda-st2-expand-panels__num {
  border-color: #e4ff54;
  color: #e4ff54;
}

.nuda-st2-expand-panels__title {
  color: #a0a0a8;
  font-size: 12px;
  font-weight: 500;
  transition: color .3s;
}

.nuda-st2-expand-panels li.is-active .nuda-st2-expand-panels__title {
  color: #fafafa;
}

.nuda-st2-expand-panels__sr {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
}

.nuda-st2-expand-panels__body {
  display: grid;
  grid-template-rows: 1fr;
  opacity: 1;
  transition: grid-template-rows .4s cubic-bezier(.16,1,.3,1),opacity .3s ease;
}

.nuda-st2-expand-panels__body>p {
  margin: 0;
  padding: 0 14px 12px;
  color: #a0a0a8;
  font-size: 11px;
  min-height: 0;
  overflow: hidden;
}

.nuda-st2-expand-panels__body button {
  margin: 0 14px 14px;
  padding: 9px 14px;
  min-height: 38px;
  background: #e4ff54;
  color: #09090b;
  border: 0;
  border-radius: 8px;
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  transition: filter .2s,transform .15s;
}

.nuda-st2-expand-panels__body button:hover {
  filter: brightness(1.08);
  transform: translateY(-1px);
}

.nuda-st2-expand-panels__body button:focus-visible {
  outline: 2px solid #e4ff54;
  outline-offset: 2px;
}

.nuda-st2-expand-panels li:not(.is-active) .nuda-st2-expand-panels__body {
  grid-template-rows: 0fr;
  opacity: 0;
}

.nuda-st2-expand-panels li:not(.is-active) .nuda-st2-expand-panels__body>p,.nuda-st2-expand-panels li:not(.is-active) .nuda-st2-expand-panels__body button {
  padding-top: 0;
  padding-bottom: 0;
  margin-bottom: 0;
  visibility: hidden;
}

@media (prefers-reduced-motion:reduce) {
  .nuda-st2-expand-panels__body {
    transition: opacity .15s linear;
  }
}