:root {
  color-scheme: dark;
  --bg: #171a1f; --panel: #282c34; --panel2: #21252b; --line: #3e4451;
  --text: #d7dae0; --muted: #a8afbc; --cyan: #56b6c2; --yellow: #e5c07b;
  --green: #98c379; --red: #e06c75; --purple: #c678dd; --blue: #61afef;
  --board: #1d2128; --control: #2c313c; --white: #f5f7fa;
  --current: #1e4752; --visited: #294232; --selected: #44364e;
}
* { box-sizing: border-box; }
body { margin: 0; min-height: 100vh; background: radial-gradient(circle at 15% 0, #283445 0, transparent 35%), linear-gradient(145deg, #171a1f, #20252d); color: var(--text); font: 15px/1.55 Inter, ui-sans-serif, system-ui, -apple-system, "Segoe UI", sans-serif; }
button, select, input { font: inherit; }
button, select, input[type=range] { min-height: 44px; max-width: 100%; border: 1px solid var(--line); border-radius: 10px; padding: 8px 12px; background: var(--control); color: var(--white); cursor: pointer; touch-action: manipulation; }
button:hover:not(:disabled), select:hover { border-color: var(--cyan); }
button:disabled { cursor: default; opacity: .4; }
button:focus-visible, select:focus-visible, input:focus-visible, [tabindex]:focus-visible { outline: 3px solid var(--cyan); outline-offset: 3px; }
button.primary { background: linear-gradient(135deg, var(--blue), var(--cyan)); color: #14202b; border: 0; font-weight: 850; }
.app { width: min(1180px, calc(100% - 28px)); margin: 22px auto 38px; }
.hero, .card { border: 1px solid var(--line); background: color-mix(in srgb, var(--panel) 95%, transparent); box-shadow: 0 18px 50px #090b1066; }
.hero { position: relative; overflow: hidden; border-radius: 22px; padding: 25px 27px; }
.hero::after { content: "↳"; position: absolute; right: 26px; top: -16px; font: 900 120px/1 ui-monospace, monospace; color: #61afef0c; pointer-events: none; }
.eyebrow { color: var(--cyan); font-weight: 800; letter-spacing: .12em; text-transform: uppercase; font-size: .78rem; }
h1 { margin: 2px 0 8px; color: var(--white); font-size: clamp(1.8rem, 4vw, 2.6rem); line-height: 1.2; }
.hero p { max-width: 800px; margin: 0; color: var(--muted); }
.layout { display: grid; grid-template-columns: minmax(0, 1.65fr) minmax(270px, .85fr); gap: 16px; margin-top: 16px; }
.card { min-width: 0; border-radius: 18px; padding: 17px; }
.side { min-width: 0; display: flex; flex-direction: column; gap: 16px; }
body[data-demo=forest] .layout, body[data-demo=flatten] .layout { grid-template-columns: minmax(0, 1fr); }
body[data-demo=forest] .side, body[data-demo=flatten] .side { display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); align-items: start; }
.toolbar, .controls, .legend, .stats { display: flex; flex-wrap: wrap; gap: 9px; align-items: center; }
.toolbar { margin-bottom: 13px; }
.toolbar label { display: grid; gap: 4px; color: var(--muted); font-size: .85rem; max-width: 100%; min-width: 0; }
.toolbar label:first-child { flex: 1 1 220px; }
.toolbar label:last-child { flex: 1 1 190px; }
.controls { border-top: 1px solid var(--line); padding-top: 13px; margin: 10px 0 14px; }
.controls button { flex: 1 1 auto; }
.controls input[type=range] { width: 100%; flex: 1 1 150px; min-width: 0; accent-color: var(--purple); }
.controls select { flex: 0 1 120px; }
.meta { display: flex; gap: 8px; justify-content: space-between; align-items: center; color: var(--muted); font-size: .88rem; margin-bottom: 8px; }
.badge { border: 1px solid var(--line); border-radius: 999px; padding: 2px 9px; color: var(--yellow); background: #e5c07b12; white-space: nowrap; }
.badge.done { color: var(--green); background: #98c37912; }
.narration { min-height: 86px; border-left: 4px solid var(--cyan); border-radius: 9px; background: var(--panel2); padding: 12px 13px; color: var(--white); overflow-wrap: anywhere; }
.compare { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; margin-top: 14px; }
.compare.single { grid-template-columns: minmax(0, 1fr); }
.pane { min-width: 0; }
.pane h2, .side h2 { margin: 0 0 8px; color: var(--white); font-size: .96rem; }
.board { min-width: 0; background: var(--board); border: 1px solid var(--line); border-radius: 14px; padding: 4px; }
.board svg { display: block; width: 100%; height: auto; min-height: 200px; max-height: 520px; }
.node { cursor: pointer; }
.node circle { fill: var(--panel); stroke: var(--muted); stroke-width: 1.6; transition: fill .18s, stroke .18s; }
.node.visited circle { fill: var(--visited); stroke: var(--green); }
.node.selected circle { fill: var(--selected); stroke: var(--purple); stroke-width: 3; }
.node.current circle { fill: var(--current); stroke: var(--cyan); stroke-width: 3; }
.node circle.selection-ring { fill: none; stroke: var(--purple); stroke-width: 2; }
.node text { fill: var(--white); font: 800 17px ui-monospace, monospace; text-anchor: middle; pointer-events: none; }
.node .node-tag { font: 600 11px ui-monospace, monospace; fill: var(--muted); }
.node .pointer-label { font: 700 12px ui-monospace, monospace; fill: var(--yellow); }
.edge { fill: none; stroke: var(--muted); stroke-width: 1.8; }
.edge.predecessor { stroke: var(--purple); stroke-dasharray: 6 5; }
.edge.successor { stroke: var(--cyan); stroke-dasharray: 6 5; }
.edge.temporary { stroke: var(--yellow); stroke-dasharray: 8 5; }
.edge.sibling { stroke: var(--purple); stroke-dasharray: 6 4; }
.edge.first-child { stroke: var(--cyan); }
.edge.added { stroke: var(--green); stroke-width: 3.5; }
.edge.removed { stroke: var(--red); stroke-dasharray: 4 5; stroke-width: 2.5; }
.edge-label { fill: var(--muted); font: 600 11px ui-monospace, monospace; text-anchor: middle; paint-order: stroke; stroke: var(--board); stroke-width: 4px; stroke-linejoin: round; }
.removed-cross { stroke: var(--red); stroke-width: 3; }
.empty-label { fill: var(--muted); font: 15px system-ui, sans-serif; text-anchor: middle; }
.legend { margin: 12px 0; color: var(--muted); font-size: .8rem; gap: 8px 14px; }
.key { display: inline-flex; align-items: center; gap: 5px; }
.swatch { width: 22px; border-top: 3px solid var(--muted); }
.swatch.predecessor { border-color: var(--purple); border-top-style: dashed; }
.swatch.successor { border-color: var(--cyan); border-top-style: dashed; }
.swatch.first-child { border-color: var(--cyan); }
.swatch.temporary { border-color: var(--yellow); border-top-style: dashed; }
.swatch.added { border-color: var(--green); }
.swatch.removed { border-color: var(--red); border-top-style: dashed; }
.seqview { display: flex; gap: 5px; flex-wrap: wrap; min-height: 40px; margin: 8px 0 0; align-items: center; }
.tok { padding: 3px 9px; border: 1px solid var(--line); border-radius: 7px; background: var(--panel2); font: 800 13px/1.5 ui-monospace, monospace; color: var(--green); }
.tok:last-child { border-color: var(--green); }
.sequence-label { color: var(--muted); font-size: .8rem; margin-top: 10px; }
.stats { margin: 12px 0; align-items: stretch; }
.stat { flex: 1 1 70px; min-width: 0; background: var(--panel2); border-radius: 10px; padding: 7px 9px; }
.stat small { display: block; color: var(--muted); }
.stat strong { color: var(--white); overflow-wrap: anywhere; }
.tip { margin: 10px 0 0; color: var(--muted); font-size: .84rem; overflow-wrap: anywhere; }
.code-steps { margin: 0; padding: 0; counter-reset: line; list-style: none; }
.code-steps li { counter-increment: line; display: flex; gap: 8px; padding: 7px 8px; border-left: 3px solid transparent; color: var(--muted); border-radius: 4px; font: 12px/1.6 ui-monospace, monospace; overflow-wrap: anywhere; }
.code-steps li::before { content: counter(line); color: var(--muted); flex: 0 0 14px; }
.code-steps li.active { border-color: var(--cyan); background: var(--current); color: var(--white); }
.pointer-table { width: 100%; border-collapse: collapse; table-layout: fixed; font: 12px/1.5 ui-monospace, monospace; }
.pointer-table th { color: var(--muted); font-weight: 600; }
.pointer-table th, .pointer-table td { padding: 7px 3px; text-align: center; border-bottom: 1px solid var(--line); overflow-wrap: anywhere; }
.pointer-table button { min-height: 36px; padding: 3px 8px; }
.pointer-table tr.selected { background: var(--selected); }
.pointer-table td.changed { color: var(--green); font-weight: 800; }
.inspector { border-left: 3px solid var(--purple); padding-left: 10px; }
.footer-note { margin: 16px 4px 0; color: var(--muted); font-size: .8rem; }
@media (max-width: 860px) {
  .app { width: min(calc(100% - 16px), 680px); margin: 8px auto 24px; }
  .layout { grid-template-columns: minmax(0, 1fr); }
  body[data-demo=forest] .side, body[data-demo=flatten] .side { grid-template-columns: minmax(0, 1fr); }
  .hero, .card { border-radius: 14px; }
  .hero { padding: 20px; }
}
@media (max-width: 720px) { .compare { grid-template-columns: minmax(0, 1fr); } }
@media (max-width: 430px) {
  .hero::after { display: none; }
  .card { padding: 12px; }
  .controls button { flex-basis: calc(50% - 9px); }
  .toolbar label { flex-basis: 100%; }
}
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { transition: none !important; scroll-behavior: auto !important; } }