/* The same quiet dot-and-name navigation used on the home page. */
.model-page--part-nav {
  --part-nav-left: max(24px, env(safe-area-inset-left));
  --part-nav-width: 156px;
  --part-nav-space: calc(var(--part-nav-left) + var(--part-nav-width) + 16px);
}
.model-part-nav {
  position: fixed;
  top: 50%;
  left: var(--part-nav-left);
  z-index: 9;
  display: flex;
  flex-direction: column;
  gap: 6px;
  width: var(--part-nav-width);
  max-height: calc(100svh - 220px - env(safe-area-inset-bottom));
  padding: 8px 0;
  overflow: auto;
  overscroll-behavior: contain;
  transform: translateY(-50%);
}
.model-part-nav button {
  display: flex;
  flex: 0 0 auto;
  align-items: center;
  gap: 10px;
  width: 100%;
  min-height: 44px;
  margin: 0;
  padding: 8px 10px;
  border: 0;
  border-radius: var(--radius-control);
  background: transparent;
  color: var(--muted);
  font: inherit;
  font-size: 15px;
  line-height: 1.5;
  text-align: left;
  cursor: pointer;
  transition: color 180ms ease;
}
.model-part-nav button::before {
  content: "";
  flex: 0 0 5px;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--accent);
  opacity: .3;
  transition: opacity 180ms ease;
}
.model-part-nav__label { min-width: 0; overflow-wrap: anywhere; }
.model-part-nav button:hover,
.model-part-nav button[aria-current="true"] { color: var(--accent); background: transparent; }
.model-part-nav button:hover::before { opacity: .8; }
.model-part-nav button[aria-current="true"] { font-weight: 600; }
.model-part-nav button[aria-current="true"]::before { opacity: 1; }
.model-part-nav button:focus-visible { outline: 2px solid var(--accent); outline-offset: -2px; }

@media (max-width: 1100px) {
  .model-page--part-nav { --part-nav-left: max(14px, env(safe-area-inset-left)); --part-nav-width: 124px; }
  .model-page--part-nav .model-stage__core {
    left: calc((100% + var(--part-nav-space)) / 2);
    width: min(var(--model-width), calc(100% - var(--part-nav-space) - 24px));
  }
}
@media (prefers-reduced-motion: reduce) {
  .model-part-nav button, .model-part-nav button::before { transition: none; }
}