/* ============================================================
   SCROLL RAIL — shared across the site.
   A thin verdigris rail down the right edge with section dots.
   Each dot has a label that fades in on hover or when active.
   Auto-flips to a light treatment over dark sections via
   IntersectionObserver (see scroll-rail.js).
   ============================================================ */

.scroll-rail {
  position: fixed;
  right: 18px;
  top: 50%;
  transform: translateY(-50%) translateX(8px);
  z-index: 49;
  display: flex; flex-direction: column; align-items: flex-end;
  gap: 2px;
  opacity: 0; pointer-events: none;
  transition: opacity 320ms ease, transform 320ms ease;
  /* verdigris hairline running through the centre of the dots */
  background: linear-gradient(180deg, transparent 0, transparent 8px,
                              rgba(74,107,92,0.32) 8px,
                              rgba(74,107,92,0.32) calc(100% - 8px),
                              transparent calc(100% - 8px));
  background-size: 1px 100%;
  background-repeat: no-repeat;
  background-position: right 9px top;
  padding: 6px 0;
}
.scroll-rail.is-visible {
  opacity: 1; pointer-events: auto;
  transform: translateY(-50%) translateX(0);
}
.scroll-rail .dot {
  position: relative;
  display: flex; align-items: center;
  text-decoration: none;
  color: var(--paper-warm, #6B5538);
  padding: 8px 0 8px 14px;
  cursor: pointer;
  background: none; border: none;
  font: inherit;
}
.scroll-rail .dot .pip {
  width: 8px; height: 8px;
  border-radius: 50%;
  background: var(--paper, #FBF1D7);
  border: 1px solid var(--filament, #B68A3E);
  box-shadow: 0 0 0 2px var(--paper, #FBF1D7);
  margin-right: 10px;
  transition: all 200ms ease;
  order: 2;
}
.scroll-rail .dot.is-active .pip {
  background: var(--accent, #4A6B5C);
  border-color: var(--filament, #B68A3E);
  box-shadow:
    0 0 0 2px var(--paper, #FBF1D7),
    0 0 0 3px rgba(182,138,62,0.55),
    0 0 10px rgba(74,107,92,0.60);
  transform: scale(1.15);
}
.scroll-rail .dot .label {
  order: 1;
  font-family: 'JetBrains Mono', monospace;
  font-size: 10px; letter-spacing: 0.20em; text-transform: uppercase;
  color: var(--paper-warm, #6B5538);
  background: var(--paper, #FBF1D7);
  border: 1px solid var(--rule, rgba(40,28,8,0.12));
  padding: 4px 9px 3px;
  margin-right: 8px;
  opacity: 0;
  transform: translateX(8px);
  transition: opacity 200ms ease, transform 200ms ease;
  pointer-events: none;
  white-space: nowrap;
  box-shadow: 0 4px 10px -6px rgba(40,28,8,0.4);
}
.scroll-rail .dot:hover .label,
.scroll-rail .dot.is-active .label {
  opacity: 1; transform: translateX(0);
}
.scroll-rail .dot.is-active .label { color: var(--accent, #4A6B5C); }
.scroll-rail .dot:focus-visible .pip {
  outline: 2px solid var(--accent, #4A6B5C); outline-offset: 3px;
}

/* Dark-section auto-flip — lighter verdigris treatment for visibility on walnut. */
body.scroll-on-dark .scroll-rail {
  background: linear-gradient(180deg, transparent 0, transparent 8px,
                              rgba(127,165,147,0.45) 8px,
                              rgba(127,165,147,0.45) calc(100% - 8px),
                              transparent calc(100% - 8px));
  background-size: 1px 100%;
  background-repeat: no-repeat;
  background-position: right 9px top;
}
body.scroll-on-dark .scroll-rail .dot .pip {
  background: rgba(20,12,4,0.65);
  border-color: var(--filament, #B68A3E);
  box-shadow: 0 0 0 2px rgba(20,12,4,0.4);
}
body.scroll-on-dark .scroll-rail .dot.is-active .pip {
  background: #7FA593;
  border-color: var(--filament, #B68A3E);
  box-shadow:
    0 0 0 2px rgba(20,12,4,0.4),
    0 0 0 3px rgba(182,138,62,0.65),
    0 0 12px rgba(127,165,147,0.75);
}
body.scroll-on-dark .scroll-rail .dot .label {
  background: rgba(20,12,4,0.85);
  border-color: rgba(127,165,147,0.35);
  color: rgba(244,229,189,0.85);
}
body.scroll-on-dark .scroll-rail .dot.is-active .label {
  color: #7FA593;
}

@media (max-width: 720px) {
  /* Phones: hide. Long pages on phones already have natural scroll cues. */
  .scroll-rail { display: none; }
}

@media (prefers-reduced-motion: reduce) {
  .scroll-rail, .scroll-rail .dot .pip, .scroll-rail .dot .label { transition: none; }
}