/* === Custom Properties === */
:root {
  --bg-primary: #1a1a2e;
  --bg-secondary: #16213e;
  --bg-card: #1e2a45;
  --accent-gold: #c9a96e;
  --accent-gold-dim: #8a7448;
  --text-primary: #e8e4df;
  --text-secondary: #a8a4a0;
  --text-muted: #6b6865;
  --timeline-height: 100px;
  --timeline-height-mobile: 80px;
  --node-size: 12px;
  --node-size-active: 18px;
  --transition-speed: 0.4s;
  --content-max-width: 800px;
}

/* === Reset & Base === */
*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html, body {
  height: 100%;
  overflow: hidden;
}

body {
  font-family: 'Inter', system-ui, -apple-system, sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  line-height: 1.6;
  -webkit-font-smoothing: antialiased;
}

/* === App Layout === */
#app {
  display: flex;
  flex-direction: column;
  height: 100vh;
  height: 100dvh;
  position: relative;
}

/* === Header === */
#header {
  text-align: center;
  padding: 12px 24px 0;
  flex-shrink: 0;
}

#title {
  font-size: 1.1rem;
  font-weight: 600;
  color: var(--accent-gold);
  letter-spacing: 0.02em;
}

#subtitle {
  font-size: 0.75rem;
  color: var(--text-secondary);
  margin-top: 2px;
}

#disclaimer {
  font-size: 0.6rem;
  color: var(--text-muted);
  margin-top: 4px;
  max-width: 600px;
  margin-left: auto;
  margin-right: auto;
}

.lang-switch {
  font-size: 0.65rem;
  color: var(--text-muted);
  margin-top: 6px;
}

.lang-switch a {
  color: var(--accent-gold-dim);
  text-decoration: none;
  transition: color 0.2s;
}

.lang-switch a:hover {
  color: var(--accent-gold);
  text-decoration: underline;
}

.lang-active {
  color: var(--accent-gold);
  font-weight: 600;
}

.lang-sep {
  margin: 0 4px;
}

/* === Content Area === */
#content-area {
  flex: 1;
  overflow: hidden;
  position: relative;
  display: flex;
  align-items: flex-start;
  justify-content: center;
  padding: 20px 60px;
}

.milestone-content {
  width: 100%;
  max-width: var(--content-max-width);
  opacity: 1;
  transform: translateX(0);
  transition: opacity var(--transition-speed) ease, transform var(--transition-speed) ease;
  overflow-y: auto;
  max-height: 100%;
  padding: 8px 0 20px;
}

.milestone-content.slide-out-left {
  opacity: 0;
  transform: translateX(-60px);
}

.milestone-content.slide-out-right {
  opacity: 0;
  transform: translateX(60px);
}

.milestone-content.slide-in-left {
  opacity: 0;
  transform: translateX(60px);
}

.milestone-content.slide-in-right {
  opacity: 0;
  transform: translateX(-60px);
}

.milestone-date-label {
  display: inline-block;
  font-size: 0.75rem;
  font-weight: 500;
  color: var(--accent-gold);
  text-transform: uppercase;
  letter-spacing: 0.08em;
  margin-bottom: 8px;
}

.milestone-name {
  font-size: 1.6rem;
  font-weight: 700;
  line-height: 1.3;
  margin-bottom: 16px;
  color: var(--text-primary);
}

.milestone-summary {
  font-size: 0.95rem;
  line-height: 1.7;
  color: var(--text-secondary);
  margin-bottom: 24px;
}

/* === Quote Cards === */
.milestone-quotes {
  display: flex;
  flex-direction: column;
  gap: 16px;
  margin-bottom: 24px;
}

.quote-card {
  background: var(--bg-card);
  border-left: 3px solid var(--accent-gold);
  padding: 16px 20px;
  border-radius: 0 6px 6px 0;
}

.quote-text {
  font-style: italic;
  font-size: 0.9rem;
  line-height: 1.6;
  color: var(--text-primary);
  margin-bottom: 10px;
}

.quote-text::before { content: "\201C"; }
.quote-text::after { content: "\201D"; }

.quote-attribution {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--accent-gold);
}

.quote-context {
  font-size: 0.7rem;
  color: var(--text-muted);
  margin-top: 2px;
}

.quote-source {
  font-size: 0.65rem;
  color: var(--accent-gold-dim);
  text-decoration: none;
  margin-top: 4px;
  display: inline-block;
}

.quote-source:hover {
  color: var(--accent-gold);
  text-decoration: underline;
}

.quote-source-text {
  font-size: 0.65rem;
  color: var(--text-muted);
  font-style: italic;
  margin-top: 4px;
  display: inline-block;
}

/* === Video Embeds === */
.milestone-videos {
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.video-embed {
  border-radius: 8px;
  overflow: hidden;
  background: var(--bg-secondary);
}

.video-embed iframe {
  display: block;
  width: 100%;
  aspect-ratio: 16 / 9;
  border: none;
}

.video-title {
  font-size: 0.8rem;
  color: var(--text-secondary);
  padding: 10px 12px;
}

/* === Navigation Arrows === */
.nav-arrow {
  position: fixed;
  top: 50%;
  transform: translateY(calc(-50% - var(--timeline-height) / 2));
  z-index: 10;
  background: transparent;
  border: none;
  color: var(--accent-gold-dim);
  font-size: 3rem;
  cursor: pointer;
  padding: 10px;
  line-height: 1;
  transition: color 0.2s, transform 0.2s;
  user-select: none;
  -webkit-tap-highlight-color: transparent;
}

.nav-arrow:hover {
  color: var(--accent-gold);
}

.nav-arrow:disabled {
  opacity: 0.2;
  cursor: default;
}

.nav-arrow-left { left: 10px; }
.nav-arrow-right { right: 10px; }

/* === Timeline Bar === */
#timeline-bar {
  flex-shrink: 0;
  height: var(--timeline-height);
  background: var(--bg-secondary);
  border-top: 1px solid rgba(201, 169, 110, 0.15);
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 6px 0 0;
  position: relative;
}

.timeline-counter {
  font-size: 0.6rem;
  color: var(--text-muted);
  margin-bottom: 4px;
  letter-spacing: 0.05em;
}

.timeline-track {
  flex: 1;
  width: 100%;
  overflow-x: auto;
  overflow-y: hidden;
  position: relative;
  scrollbar-width: thin;
  scrollbar-color: var(--accent-gold-dim) transparent;
}

.timeline-track::-webkit-scrollbar {
  height: 4px;
}

.timeline-track::-webkit-scrollbar-track {
  background: transparent;
}

.timeline-track::-webkit-scrollbar-thumb {
  background: var(--accent-gold-dim);
  border-radius: 2px;
}

.timeline-nodes {
  display: flex;
  align-items: center;
  height: 100%;
  padding: 0 40px;
  position: relative;
  width: max-content;
  min-width: 100%;
}

.timeline-line {
  display: none; /* line drawn via node borders instead */
}

/* === Timeline Nodes === */
.timeline-node {
  display: flex;
  flex-direction: column;
  align-items: center;
  cursor: pointer;
  padding: 0 8px;
  position: relative;
  flex-shrink: 0;
  transition: transform 0.2s;
  -webkit-tap-highlight-color: transparent;
}

.timeline-node:hover {
  transform: scale(1.1);
}

.node-dot {
  width: var(--node-size);
  height: var(--node-size);
  border-radius: 50%;
  background: var(--accent-gold-dim);
  border: 2px solid var(--bg-secondary);
  transition: all 0.3s ease;
  position: relative;
  z-index: 2;
}

.timeline-node.active .node-dot {
  width: var(--node-size-active);
  height: var(--node-size-active);
  background: var(--accent-gold);
  box-shadow: 0 0 12px rgba(201, 169, 110, 0.4);
}

.timeline-node.interval .node-dot {
  border-radius: 3px;
  width: 16px;
}

.timeline-node.interval.active .node-dot {
  width: 22px;
  border-radius: 4px;
}

.node-label {
  font-size: 0.55rem;
  color: var(--text-muted);
  margin-top: 6px;
  white-space: nowrap;
  max-width: 60px;
  overflow: hidden;
  text-overflow: ellipsis;
  text-align: center;
  transition: color 0.3s;
}

.timeline-node.active .node-label {
  color: var(--accent-gold);
  font-weight: 600;
  max-width: 120px;
}

.node-year {
  font-size: 0.6rem;
  color: var(--text-muted);
  margin-top: 2px;
  opacity: 0;
  transition: opacity 0.3s;
}

.timeline-node.active .node-year {
  opacity: 1;
  color: var(--accent-gold-dim);
}

/* connector lines between nodes */
.timeline-node::before {
  content: '';
  position: absolute;
  top: calc(var(--node-size) / 2 - 1px);
  right: 100%;
  width: 8px;
  height: 2px;
  background: var(--accent-gold-dim);
  opacity: 0.3;
}

.timeline-node:first-child::before {
  display: none;
}

.timeline-node::after {
  content: '';
  position: absolute;
  top: calc(var(--node-size) / 2 - 1px);
  left: 100%;
  width: 8px;
  height: 2px;
  background: var(--accent-gold-dim);
  opacity: 0.3;
}

.timeline-node:last-child::after {
  display: none;
}

/* era separators */
.era-separator {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 0 12px;
  flex-shrink: 0;
}

.era-separator .era-label {
  font-size: 0.55rem;
  font-weight: 600;
  color: var(--accent-gold);
  text-transform: uppercase;
  letter-spacing: 0.1em;
  white-space: nowrap;
  opacity: 0.6;
}

.era-separator .era-line {
  width: 1px;
  height: 20px;
  background: var(--accent-gold);
  opacity: 0.2;
  margin-top: 4px;
}

/* === Responsive === */
@media (max-width: 768px) {
  #content-area {
    padding: 16px 20px;
  }

  .nav-arrow {
    font-size: 2rem;
    padding: 6px;
  }

  .nav-arrow-left { left: 4px; }
  .nav-arrow-right { right: 4px; }

  .milestone-name {
    font-size: 1.3rem;
  }

  #timeline-bar {
    height: var(--timeline-height-mobile);
  }

  .nav-arrow {
    transform: translateY(calc(-50% - var(--timeline-height-mobile) / 2));
  }

  .timeline-node {
    padding: 0 6px;
  }

  .node-label {
    display: none;
  }
}

@media (max-width: 480px) {
  #header {
    padding: 8px 16px 0;
  }

  #title {
    font-size: 0.95rem;
  }

  #content-area {
    padding: 12px 16px;
  }

  .milestone-name {
    font-size: 1.1rem;
  }

  .milestone-summary {
    font-size: 0.85rem;
  }

  .quote-card {
    padding: 12px 14px;
  }

  .nav-arrow {
    font-size: 1.8rem;
  }
}