/* Timeline Component Styles */
:root {
  --timeline-accent: #2563eb; /* blue accent */
  --timeline-border: rgba(148, 163, 184, 0.25); /* subtle border */
  --timeline-line: rgba(148, 163, 184, 0.3);
  --timeline-card-bg: rgba(255, 255, 255, 0.06);
  --timeline-card-bg-solid: #ffffff;
  --timeline-card-bg-dark: rgba(17, 24, 39, 0.6);
  --timeline-shadow: 0 6px 20px rgba(0, 0, 0, 0.18);
  --timeline-shadow-soft: 0 2px 10px rgba(0,0,0,0.08);
}

@media (prefers-color-scheme: light) {
  :root {
    --timeline-card-bg: var(--timeline-card-bg-solid);
    --timeline-border: rgba(15, 23, 42, 0.08);
    --timeline-line: rgba(15, 23, 42, 0.12);
    --timeline-shadow: var(--timeline-shadow-soft);
  }
}

.timeline-section {
  position: relative;
  padding: clamp(40px, 6vw, 96px) 0;
}

.timeline-section .section-header {
  text-align: center;
  margin-bottom: clamp(24px, 4vw, 40px);
}

.timeline-section .section-title {
  margin: 0 0 6px 0;
}

.timeline-section .section-subtitle {
  opacity: 0.8;
  margin: 0;
}

/* Core timeline */
.timeline {
  position: relative;
  list-style: none;
  padding: 0;
  margin: 0;
  /* progress height (px) will be set by JS */
  --progress-px: 0px;
}

/* Center line */
.timeline::before {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: 50%;
  width: 2px;
  transform: translateX(-50%);
  background: linear-gradient(
    to bottom,
    transparent 0%,
    var(--timeline-line) 10%,
    var(--timeline-line) 90%,
    transparent 100%
  );
}

/* Scroll progress fill line */
.timeline::after {
  content: "";
  position: absolute;
  top: 0;
  left: 50%;
  transform: translateX(-50%);
  width: 4px;
  height: var(--progress-px, 0px);
  background: linear-gradient(
    to bottom,
    color-mix(in oklab, var(--timeline-accent), #ffffff 10%) 0%,
    var(--timeline-accent) 100%
  );
  box-shadow: 0 0 0 3px color-mix(in oklab, var(--timeline-accent), transparent 85%),
              0 6px 18px color-mix(in oklab, var(--timeline-accent), transparent 60%);
  border-radius: 999px;
  pointer-events: none;
}

.timeline-item {
  position: relative;
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: clamp(16px, 2.5vw, 32px);
  align-items: center;
  padding: clamp(12px, 2.2vw, 22px) 0;
}

/* Connector arms from spine to cards */
.timeline-item::before {
  content: "";
  position: absolute;
  top: 50%;
  height: 2px;
  background: var(--timeline-line);
}
.timeline-item:nth-child(odd)::before {
  left: 50%;
  transform: translateX(-100%);
  width: clamp(48px, 12vw, 140px);
}
.timeline-item:nth-child(even)::before {
  left: 50%;
  width: clamp(48px, 12vw, 140px);
}

/* Marker for each event */
.timeline-item::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  width: 14px;
  height: 14px;
  background: var(--timeline-accent);
  border: 2px solid color-mix(in oklab, var(--timeline-accent), #fff 30%);
  border-radius: 999px;
  box-shadow: 0 0 0 4px color-mix(in oklab, var(--timeline-accent), transparent 80%),
              0 4px 16px rgba(0, 0, 0, 0.18);
}

/* Ripple effect when progress passes a marker */
@keyframes marker-ripple {
  0% {
    box-shadow: 0 0 0 4px color-mix(in oklab, var(--timeline-accent), transparent 75%),
                0 0 0 10px color-mix(in oklab, var(--timeline-accent), transparent 92%),
                0 4px 16px rgba(0, 0, 0, 0.18);
  }
  100% {
    box-shadow: 0 0 0 4px color-mix(in oklab, var(--timeline-accent), transparent 90%),
                0 0 0 20px color-mix(in oklab, var(--timeline-accent), transparent 100%),
                0 4px 16px rgba(0, 0, 0, 0.18);
  }
}
.timeline-item.passed::after {
  animation: marker-ripple 850ms ease-out 1;
}

.timeline-card {
  background: var(--timeline-card-bg);
  border: 1px solid var(--timeline-border);
  border-radius: 16px;
  box-shadow: var(--timeline-shadow);
  padding: clamp(12px, 1.8vw, 20px);
  max-width: min(960px, 96vw);
  opacity: 0;
  transform: translateY(14px);
}

/* Keep long titles to a single line on wide viewports */
@media (min-width: 1200px) {
  .timeline-card .headline {
    white-space: nowrap;
  }
}

.timeline-card .meta {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 6px;
}

.timeline-card .year {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-weight: 700;
  font-size: 0.95rem;
  color: var(--timeline-accent);
}

.timeline-card .year::before {
  content: "";
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 999px;
  background: var(--timeline-accent);
  box-shadow: 0 0 0 3px color-mix(in oklab, var(--timeline-accent), transparent 75%);
}

.timeline-card .headline {
  margin: 4px 0 4px 0;
  font-size: clamp(1rem, 1.6vw, 1.15rem);
}

.timeline-card .description {
  margin: 0;
  opacity: 0.9;
  line-height: 1.45;
}

/* Alternating placement */
.timeline-item:nth-child(odd) .timeline-card {
  grid-column: 1 / 2;
  justify-self: end;
  text-align: right;
}

.timeline-item:nth-child(even) .timeline-card {
  grid-column: 2 / 3;
  justify-self: start;
  text-align: left;
}

/* Reveal animation */
@media (prefers-reduced-motion: no-preference) {
  .timeline-card {
    transition: opacity 480ms ease, transform 520ms cubic-bezier(0.22, 1, 0.36, 1);
  }
}

.timeline-item.in-view .timeline-card {
  opacity: 1;
  transform: translateY(0);
}

/* Mobile layout */
@media (max-width: 900px) {
  .timeline::before {
    left: 24px;
    transform: none;
  }
  .timeline::after {
    left: 24px;
    transform: none;
  }
  .timeline-item::before {
    left: 24px;
    transform: none;
    width: 16px;
  }
  .timeline-item {
    grid-template-columns: 1fr;
    align-items: start;
    padding-left: 12px; /* room for marker */
  }
  .timeline-item::after {
    left: 24px;
  }
  .timeline-card {
    grid-column: 1 / -1 !important;
    justify-self: start !important;
    text-align: left !important;
    margin-left: 32px; /* offset from center line */
    max-width: 720px;
  }
}

/* Focus styles for accessibility */
.timeline-card:focus-within,
.timeline-card:focus {
  outline: 2px solid color-mix(in oklab, var(--timeline-accent), #ffffff 20%);
  outline-offset: 2px;
}

/* Utility container alignment to match site's layout */
.timeline-section .container {
  max-width: 1400px;
  margin: 0 auto;
  padding-left: clamp(16px, 4vw, 32px);
  padding-right: clamp(16px, 4vw, 32px);
}