/* The host .zt-case reserves its existing 104px chapter gutter. */
.zt-case { position: relative; }
.zt-nav {
  --zt-nav-progress: 0;
  --zt-nav-track-top: 22px;
  --zt-nav-track-length: 58px;
  --zt-nav-marker-y: 10px;
  --zt-nav-accent: var(--accent, #007aff);
  position: absolute;
  z-index: 6;
  left: 0;
  top: var(--zt-nav-top, clamp(165px, 30vh, 320px));
  display: grid;
  gap: 14px;
  width: 98px;
  margin: 0;
  padding: 0;
  color: var(--ink-muted);
  font-family: var(--zt-font, var(--sans));
}
.zt-nav-track {
  position: absolute;
  left: 11px;
  top: var(--zt-nav-track-top);
  width: 2px;
  height: var(--zt-nav-track-length);
  border-radius: 2px;
  overflow: hidden;
  background: color-mix(in srgb, var(--bg) 12%, transparent);
  pointer-events: none;
}
.zt-nav-fill {
  display: block;
  width: 100%;
  height: 100%;
  border-radius: inherit;
  background: var(--zt-nav-accent);
  transform: scaleY(var(--zt-nav-progress));
  transform-origin: top;
}
.zt-nav-marker {
  position: absolute;
  z-index: 1;
  left: 0;
  top: var(--zt-nav-marker-y);
  width: 24px;
  height: 24px;
  border-radius: 50%;
  object-fit: cover;
  transform: none !important;
  transition: top .2s ease;
  pointer-events: none;
  user-select: none;
}
.zt-nav-button {
  position: relative;
  display: flex;
  align-items: center;
  width: 100%;
  min-height: 44px;
  margin: 0;
  padding: 0 0 0 31px;
  appearance: none;
  border: 0;
  border-radius: 3px;
  color: var(--ink-muted);
  background: transparent;
  font: 400 12px/1.5 var(--zt-font, var(--sans));
  text-align: left;
  cursor: pointer;
  visibility: visible !important;
}
.zt-nav-button > span { min-width: 0; }
.zt-nav-button:hover, .zt-nav-button.is-current { color: var(--bg); }
.zt-nav-button.is-current { font-weight: 600; }
.zt-nav-button:focus-visible { outline: 2px solid var(--zt-nav-accent); outline-offset: 3px; }
@media (max-width: 859px) {
  .zt-nav { display: none; }
}
@media (prefers-reduced-motion: reduce) {
  .zt-nav-marker { transition: none; }
}