nav.cs-rail {
  position: fixed;
  left: 24px;
  top: 50%;
  transform: translateY(-50%);
  display: flex;
  align-items: flex-start;
  flex-direction: column;
  gap: 8px;
  width: max-content;
  max-height: 90vh;
  overflow-y: auto;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.4s ease;
  z-index: 10;
}

nav.cs-rail.is-visible {
  opacity: 1;
  pointer-events: auto;
}

.cs-rail a {
  display: block;
  font-family: 'Gambarino', serif;
  font-size: 16px;
  line-height: 1.4;
  text-decoration: none;
  color: #a1a1a1;
  opacity: 0.4;
  white-space: nowrap;
  transition: color 0.3s ease, opacity 0.3s ease, font-size 0.3s ease;
}

.cs-rail a.is-active {
  color: #81d83d;
  opacity: 1;
  font-size: 24px;
}

.cs-rail a:not(.is-active):hover {
  opacity: 0.75;
}

@media (max-width: 1079px) {
  nav.cs-rail { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  nav.cs-rail, .cs-rail a { transition: none; }
}