@import url('https://fonts.googleapis.com/css2?family=Noto+Serif+SC:wght@400;600;700;900&family=Noto+Sans+SC:wght@300;400;500;700&display=swap');

  :root {
    --bg: #faf8f5;
    --bg-dark: #f0ece6;
    --text: #2c2c2c;
    --text-light: #6b6b6b;
    --text-muted: #999;
    --border: #e0dcd6;
    --panel-bg: #fff;
    --shadow: 0 4px 24px rgba(0,0,0,0.08);
    --radius: 12px;
  }

  * { margin: 0; padding: 0; box-sizing: border-box; }

  body {
    font-family: 'Noto Sans SC', -apple-system, sans-serif;
    background: var(--bg);
    color: var(--text);
    overflow: hidden;
    height: 100vh;
    display: flex;
  }

  /* ─── Sidebar ─── */
  .sidebar {
    width: 220px;
    height: 100vh;
    background: var(--panel-bg);
    border-right: 1px solid var(--border);
    display: flex;
    flex-direction: column;
    flex-shrink: 0;
    z-index: 50;
  }

  .sidebar-header {
    padding: 16px;
    border-bottom: 1px solid var(--border);
  }

  .sidebar-header h1 {
    font-family: 'Noto Serif SC', serif;
    font-size: 18px;
    font-weight: 900;
    letter-spacing: 2px;
  }

  .sidebar-header .sub {
    font-size: 11px;
    color: var(--text-muted);
    margin-top: 2px;
  }

  .sidebar-search {
    padding: 8px 12px;
    border-bottom: 1px solid var(--border);
  }

  .sidebar-search input {
    width: 100%;
    padding: 6px 10px;
    border: 1px solid var(--border);
    border-radius: 6px;
    font-size: 13px;
    outline: none;
    background: var(--bg);
  }

  .sidebar-search input:focus { border-color: #457b9d; }

  .sidebar-body {
    flex: 1;
    overflow-y: auto;
    padding: 8px 0;
  }

  .sidebar-body::-webkit-scrollbar { width: 4px; }
  .sidebar-body::-webkit-scrollbar-thumb { background: var(--border); border-radius: 2px; }

  .group-header {
    padding: 6px 16px;
    font-size: 11px;
    font-weight: 700;
    color: var(--text-muted);
    text-transform: uppercase;
    letter-spacing: 1px;
    cursor: pointer;
    display: flex;
    justify-content: space-between;
    align-items: center;
    user-select: none;
  }

  .group-header:hover { background: var(--bg-dark); }

  .group-toggle {
    font-size: 10px;
    color: var(--text-muted);
    padding: 2px 6px;
    border-radius: 3px;
    border: 1px solid var(--border);
    cursor: pointer;
  }

  .line-item {
    display: flex;
    align-items: center;
    gap: 8px;
    padding: 4px 16px;
    font-size: 12px;
    cursor: pointer;
    transition: background 0.15s;
    user-select: none;
  }

  .line-item:hover { background: var(--bg-dark); }
  .line-item.active { background: var(--bg-dark); font-weight: 500; }
  .line-item.hidden { opacity: 0.3; }

  .line-dot {
    width: 8px;
    height: 8px;
    border-radius: 50%;
    flex-shrink: 0;
  }

  .line-count {
    margin-left: auto;
    font-size: 10px;
    color: var(--text-muted);
  }

  /* ─── Main Area ─── */
  .main {
    flex: 1;
    position: relative;
    overflow: hidden;
  }

  /* Fixed timeline rulers */
  .timeline-ruler {
    position: absolute;
    left: 0;
    right: 0;
    height: 32px;
    background: linear-gradient(to bottom, rgba(250, 248, 245, 0.98), rgba(250, 248, 245, 0.95));
    backdrop-filter: blur(8px);
    border-bottom: 1px solid var(--border);
    z-index: 100;
    pointer-events: none;
    overflow: hidden;
    display: flex;
    align-items: center;
  }

  .timeline-top {
    top: 0;
    border-bottom: 1px solid var(--border);
  }

  .timeline-bottom {
    bottom: 0;
    border-top: 1px solid var(--border);
    border-bottom: none;
  }

  .timeline-ruler .year-marker {
    position: absolute;
    text-align: center;
    font-size: 11px;
    font-weight: 600;
    color: var(--text-muted);
    white-space: nowrap;
    pointer-events: none;
  }

  svg {
    width: 100%;
    height: 100%;
    cursor: grab;
  }

  svg:active { cursor: grabbing; }

  .line-path {
    fill: none;
    stroke-width: 2.5;
    stroke-linecap: round;
    opacity: 0.7;
    transition: opacity 0.3s;
  }

  .line-path.dimmed { opacity: 0.06; }
  .line-path.highlighted { opacity: 1; stroke-width: 3.5; }

  .station {
    cursor: pointer;
    transition: opacity 0.3s;
  }

  .station.dimmed { opacity: 0.06; }

  .station-dot {
    transition: r 0.15s;
  }

  .station:hover .station-dot { r: var(--hover-r, 7); }

  .interchange-halo {
    pointer-events: none;
    transition: r 0.15s;
  }

  .station-label {
    font-family: 'Noto Sans SC', sans-serif;
    font-size: 9px;
    fill: var(--text-light);
    pointer-events: none;
    transition: opacity 0.2s;
  }

  .station-label.dimmed { opacity: 0.06; }
  .station-label.zoom-hidden { display: none; }
  .station-label.lbl-v { font-size: 8px; writing-mode: vertical-rl; }
  .station-label.lbl-count { font-size: 8px; fill: #aaa; font-style: italic; letter-spacing: 0; }

  /* Cluster merge: members hidden when zoomed out */
  .cluster-hidden { display: none; }
  .cluster-badge-bg { fill: #888; opacity: 0.85; display: none; }
  .cluster-badge-text {
    font-size: 6px; fill: #fff; font-weight: bold;
    pointer-events: none; dominant-baseline: middle;
    text-anchor: middle; display: none;
  }

  .transfer-line { pointer-events: none; }
  .transfer-line.chain-sequel { stroke: #2a7a2a; }
  .transfer-line.chain-causal { stroke: #c0392b; }
  .transfer-line.chain-part_of { stroke: #e67e22; }
  .transfer-line.chain-opposition { stroke: #8e44ad; }

  .transfer-marker {
    cursor: pointer;
  }

  /* Year grid lines */
  .year-grid {
    stroke: #e8e4de;
    stroke-width: 0.5;
    opacity: 0.6;
  }

  /* Year labels - both top and bottom */
  .year-label-top,
  .year-label-bottom {
    font-family: 'Noto Sans SC', sans-serif;
    font-size: 11px;
    font-weight: 500;
    fill: var(--text-muted);
    pointer-events: none;
  }

  .year-label-bottom {
    font-weight: 600;
  }

  .line-label-bg { rx: 3; ry: 3; }
  .line-label-text {
    font-family: 'Noto Serif SC', serif;
    font-size: 11px;
    font-weight: 700;
    fill: white;
  }

  /* ─── Detail Panel ─── */
  .detail-panel {
    position: absolute;
    right: 16px;
    top: 16px;
    width: 340px;
    max-height: calc(100vh - 32px);
    background: var(--panel-bg);
    border-radius: var(--radius);
    box-shadow: var(--shadow);
    border: 1px solid var(--border);
    overflow-y: auto;
    transform: translateX(380px);
    transition: transform 0.3s cubic-bezier(0.4, 0, 0.2, 1);
    z-index: 40;
  }

  .detail-panel.open { transform: translateX(0); }

  .panel-close {
    position: absolute;
    top: 12px; right: 12px;
    width: 28px; height: 28px;
    border: none;
    background: var(--bg-dark);
    border-radius: 50%;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    color: var(--text-light);
  }

  .panel-close:hover { background: var(--border); }

  .panel-header {
    padding: 16px 16px 12px;
    border-bottom: 1px solid var(--border);
  }

  .panel-title {
    font-family: 'Noto Serif SC', serif;
    font-size: 17px;
    font-weight: 700;
    padding-right: 32px;
    line-height: 1.4;
  }

  .panel-meta {
    display: flex;
    flex-wrap: wrap;
    gap: 4px;
    margin-top: 6px;
  }

  .meta-tag {
    padding: 2px 8px;
    border-radius: 4px;
    font-size: 11px;
    background: var(--bg-dark);
    color: var(--text-light);
  }

  .panel-body { padding: 12px 16px 16px; }

  .panel-section { margin-bottom: 12px; }

  .panel-section-title {
    font-size: 10px;
    font-weight: 600;
    color: var(--text-muted);
    letter-spacing: 1px;
    margin-bottom: 4px;
    text-transform: uppercase;
  }

  .entity-list {
    display: flex;
    flex-wrap: wrap;
    gap: 4px;
  }

  .entity-tag {
    padding: 2px 8px;
    border-radius: 12px;
    font-size: 11px;
    cursor: pointer;
    transition: transform 0.15s;
    text-decoration: none;
    color: inherit;
  }

  .entity-tag:hover { transform: scale(1.05); }
  .entity-tag.person { background: #eef; color: #446; }
  .entity-tag.location { background: #efe; color: #464; }
  .entity-tag.dynasty { background: #fee; color: #644; }

  .quote-box {
    background: var(--bg-dark);
    border-left: 3px solid var(--border);
    padding: 8px 12px;
    font-size: 13px;
    line-height: 1.6;
    color: var(--text-light);
    font-family: 'Noto Serif SC', serif;
    border-radius: 0 6px 6px 0;
  }

  .description-text {
    font-size: 13px;
    line-height: 1.6;
    color: var(--text);
  }

  .para-link {
    display: inline-block;
    margin-top: 4px;
    font-size: 11px;
    color: #457b9d;
    text-decoration: none;
  }

  .para-link:hover { text-decoration: underline; }

  .related-list { list-style: none; }

  .related-list li {
    padding: 4px 0;
    border-bottom: 1px solid var(--bg-dark);
    font-size: 12px;
    cursor: pointer;
  }

  .related-list li:hover { color: #457b9d; }

  .rel-badge {
    font-size: 10px;
    padding: 1px 5px;
    border-radius: 3px;
    margin-right: 3px;
    font-weight: 500;
  }

  .rel-badge.sequel { background: #e8f4e8; color: #2a7a2a; }
  .rel-badge.causal { background: #fde8e8; color: #a33; }
  .rel-badge.part_of { background: #fdf3e8; color: #a73; }
  .rel-badge.opposition { background: #f3e8fd; color: #73a; }
  .rel-badge.cross_ref { background: #e8e8f0; color: #555; }
  .rel-badge.co_person { background: #e8f0fd; color: #457b9d; }
  .rel-badge.co_location { background: #e8fdf3; color: #2a9d8f; }
  .rel-badge.concurrent { background: #fde8e0; color: #e76f51; }

  /* ─── Tooltip ─── */
  .tooltip {
    position: fixed;
    padding: 6px 12px;
    background: rgba(30,30,30,0.92);
    color: white;
    border-radius: 6px;
    font-size: 12px;
    pointer-events: none;
    opacity: 0;
    transition: opacity 0.12s;
    z-index: 200;
    max-width: 240px;
    line-height: 1.3;
  }

  .tooltip.visible { opacity: 1; }
  .tooltip .tt-sub { font-size: 10px; opacity: 0.7; }

  /* ─── Bottom bar ─── */
  .bottom-bar {
    position: absolute;
    bottom: 12px;
    left: 50%;
    transform: translateX(-50%);
    background: var(--panel-bg);
    padding: 6px 16px;
    border-radius: 16px;
    box-shadow: var(--shadow);
    font-size: 13px;
    display: flex;
    align-items: center;
    gap: 12px;
    z-index: 30;
  }

  .bottom-bar .era { font-size: 11px; color: var(--text-muted); }

  .zoom-controls {
    position: absolute;
    bottom: 12px;
    right: 16px;
    display: flex;
    gap: 4px;
    z-index: 30;
  }

  .zoom-btn {
    width: 32px;
    height: 32px;
    border: 1px solid var(--border);
    background: var(--panel-bg);
    border-radius: 6px;
    cursor: pointer;
    font-size: 16px;
    display: flex;
    align-items: center;
    justify-content: center;
    color: var(--text-light);
  }

  .zoom-btn:hover { background: var(--bg-dark); }

  .stats {
    position: absolute;
    top: 12px;
    left: 12px;
    font-size: 11px;
    color: var(--text-muted);
    z-index: 30;
  }