/* ============================================
   TIMELINE — Interactive Chronological View
   ============================================ */

/* ---- Timeline Controls ---- */
.timeline-controls {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-sm);
  justify-content: center;
  margin-bottom: var(--space-3xl);
}

.timeline-filter {
  padding: var(--space-xs) var(--space-lg);
  font-family: var(--font-ui);
  font-size: var(--text-xs);
  font-weight: var(--weight-semibold);
  letter-spacing: var(--tracking-wider);
  text-transform: uppercase;
  color: var(--color-text-muted);
  background: transparent;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-full);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.timeline-filter:hover {
  color: var(--color-text-secondary);
  border-color: var(--color-border-strong);
}

.timeline-filter.active {
  color: var(--color-text-inverse);
  background: var(--color-gold);
  border-color: var(--color-gold);
}

/* ---- Timeline Track ---- */
.timeline-track {
  position: relative;
  padding: var(--space-xl) 0;
}

/* Central vertical line */
.timeline-track::before {
  content: '';
  position: absolute;
  top: 0;
  bottom: 0;
  left: 20px;
  width: 1px;
  background: linear-gradient(180deg,
    transparent,
    var(--color-gold-dim) 5%,
    var(--color-gold-dim) 95%,
    transparent
  );
}

@media (min-width: 1024px) {
  .timeline-track::before {
    left: 50%;
    transform: translateX(-50%);
  }
}

/* ---- Timeline Item ---- */
.timeline-item {
  position: relative;
  padding-left: 50px;
  padding-bottom: var(--space-2xl);
  opacity: 1;
  transition: opacity var(--transition-base), transform var(--transition-base);
}

.timeline-item.is-hidden {
  opacity: 0;
  height: 0;
  padding: 0;
  overflow: hidden;
  transform: scale(0.95);
}

@media (min-width: 1024px) {
  .timeline-item {
    width: 50%;
    padding-left: 0;
    padding-right: var(--space-2xl);
    padding-bottom: var(--space-3xl);
  }

  /* Odd items: left side */
  .timeline-item:nth-child(odd) {
    margin-left: 0;
    padding-right: var(--space-3xl);
    text-align: right;
  }

  /* Even items: right side */
  .timeline-item:nth-child(even) {
    margin-left: 50%;
    padding-left: var(--space-3xl);
    padding-right: 0;
    text-align: left;
  }
}

/* ---- Timeline Marker ---- */
.timeline-marker {
  position: absolute;
  left: 14px;
  top: 6px;
  width: 13px;
  height: 13px;
  border-radius: var(--radius-full);
  background: var(--color-bg-primary);
  border: 2px solid var(--color-gold-dim);
  z-index: 2;
  transition: all var(--transition-fast);
}

.timeline-item:hover .timeline-marker {
  background: var(--color-gold);
  border-color: var(--color-gold);
  box-shadow: 0 0 12px rgba(201, 168, 76, 0.4);
}

@media (min-width: 1024px) {
  .timeline-item:nth-child(odd) .timeline-marker {
    left: auto;
    right: calc(-6px - var(--space-3xl) + var(--space-3xl));
    right: -7px;
  }

  .timeline-item:nth-child(even) .timeline-marker {
    left: -7px;
  }
}

/* ---- Timeline Date ---- */
.timeline-date {
  font-family: var(--font-subheading);
  font-size: var(--text-lg);
  color: var(--color-gold);
  letter-spacing: var(--tracking-wide);
  margin-bottom: var(--space-xs);
}

/* ---- Timeline Content Card ---- */
.timeline-content {
  background: var(--color-bg-card);
  border: 1px solid var(--color-border-subtle);
  border-radius: var(--radius-md);
  padding: var(--space-xl);
  transition: all var(--transition-base);
  cursor: pointer;
}

.timeline-content:hover {
  border-color: var(--color-border);
  box-shadow: var(--shadow-md);
}

.timeline-content h3 {
  font-family: var(--font-subheading);
  font-size: var(--text-lg);
  color: var(--color-text-primary);
  letter-spacing: var(--tracking-wide);
  margin-bottom: var(--space-sm);
  line-height: var(--leading-snug);
}

.timeline-content p {
  font-size: var(--text-sm);
  color: var(--color-text-secondary);
  line-height: var(--leading-relaxed);
  margin-bottom: var(--space-sm);
}

.timeline-content .tag {
  margin-top: var(--space-xs);
}

/* ---- Expandable detail ---- */
.timeline-detail {
  max-height: 0;
  overflow: hidden;
  transition: max-height var(--duration-slow) var(--ease-smooth),
              padding var(--transition-base);
  padding-top: 0;
}

.timeline-item.is-expanded .timeline-detail {
  max-height: 600px;
  padding-top: var(--space-md);
}

.timeline-detail p {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
}

.timeline-detail cite {
  display: block;
  margin-top: var(--space-sm);
  font-family: var(--font-ui);
  font-size: var(--text-xs);
  color: var(--color-gold-dim);
  font-style: normal;
  letter-spacing: var(--tracking-wide);
}

.timeline-expand-hint {
  display: inline-block;
  margin-top: var(--space-sm);
  font-family: var(--font-ui);
  font-size: var(--text-xs);
  color: var(--color-gold-dim);
  letter-spacing: var(--tracking-wide);
  text-transform: uppercase;
  transition: color var(--transition-fast);
}

.timeline-item:hover .timeline-expand-hint {
  color: var(--color-gold);
}

.timeline-item.is-expanded .timeline-expand-hint {
  display: none;
}

/* ---- Year indicator (side) ---- */
.timeline-year-indicator {
  position: fixed;
  right: var(--space-xl);
  top: 50%;
  transform: translateY(-50%);
  z-index: var(--z-sticky);
  font-family: var(--font-subheading);
  font-size: var(--text-2xl);
  color: var(--color-gold-dim);
  opacity: 0.3;
  pointer-events: none;
  transition: opacity var(--transition-base);
  display: none;
}

@media (min-width: 1200px) {
  .timeline-year-indicator {
    display: block;
  }
}

/* ---- Empty state ---- */
.timeline-empty {
  text-align: center;
  padding: var(--space-4xl);
  color: var(--color-text-muted);
  font-family: var(--font-ui);
  font-size: var(--text-lg);
  display: none;
}

.timeline-empty.is-visible {
  display: block;
}