:root {
  --quiz-bg: #f5f5f2;
  --quiz-surface: #ffffff;
  --quiz-surface-raised: #f7f7f5;
  --quiz-user: #f1f2ef;
  --quiz-line: rgba(17, 24, 39, 0.11);
  --quiz-line-strong: rgba(17, 24, 39, 0.22);
  --quiz-text: #171717;
  --quiz-muted: #5f6368;
  --quiz-faint: #767b84;
  --quiz-accent: #2563eb;
  --quiz-accent-strong: #111827;
  --quiz-check: #f59e0b;
  --quiz-followup: #0ea5e9;
  --quiz-custom: #a855f7;
  --quiz-error: #dc2626;
  --quiz-radius: 16px;
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-5: 24px;
  --space-6: 32px;
  --radius-control: 10px;
  --radius-card: 16px;
  --radius-panel: 20px;
  --font-label: 11px;
  --font-body: 14px;
  --font-reading: 16px;
  --shadow-card: 0 14px 34px rgba(17,24,39,.09);
  --shadow-panel: 0 20px 54px rgba(17,24,39,.09);
  --motion-fast: 160ms;
  --motion-standard: 260ms;
  --motion-emphasis: 520ms;
  --ease-standard: cubic-bezier(.2,.7,.2,1);
  --ease-emphasis: cubic-bezier(.22,.8,.32,1);
  color-scheme: light;
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI Variable", "Segoe UI", "PingFang SC", "Microsoft YaHei UI", "Noto Sans CJK SC", sans-serif;
}

* { box-sizing: border-box; }
html, body { min-height: 100%; max-width: 100%; overflow-x: hidden; }
html, body { transition: background-color var(--motion-standard) ease, color var(--motion-fast) ease; }
body {
  margin: 0;
  background:
    radial-gradient(circle at 75% -10%, rgba(37, 99, 235, 0.07), transparent 34rem),
    var(--quiz-bg);
  color: var(--quiz-text);
}
button, input, textarea { font: inherit; }
button { cursor: pointer; }
button:disabled { cursor: not-allowed; opacity: 0.48; }
button:focus-visible, a:focus-visible, select:focus-visible, .node-card:focus-visible { outline: 3px solid rgba(37,99,235,.22); outline-offset: 2px; }
[hidden] { display: none !important; }

.quiz-shell { width: min(1840px, 100%); margin: 0 auto; padding: 42px 42px 64px; }
.eyebrow { margin: 0 0 12px; color: var(--quiz-faint); font-size: 10px; letter-spacing: 0.16em; text-transform: uppercase; }
.access-panel { position: relative; display: grid; place-content: center; min-height: calc(100vh - 106px); max-width: 500px; margin: auto; }
.access-panel h1, .study-header h1 { margin: 0; font-weight: 500; letter-spacing: -0.04em; }
.access-panel h1 { font-size: clamp(30px, 5vw, 48px); }
.access-panel > p:not(.eyebrow):not(.form-error) { margin: 18px 0 30px; color: var(--quiz-muted); line-height: 1.8; }
.access-panel label { display: block; margin-bottom: 8px; color: var(--quiz-muted); font-size: 12px; }
.access-row { display: flex; gap: 8px; }
input, textarea { width: 100%; border: 1px solid var(--quiz-line); border-radius: 11px; outline: 0; background: rgba(255,255,255,.82); color: var(--quiz-text); transition: border-color .2s, background .2s, box-shadow .2s; }
input { padding: 12px 13px; }
textarea { min-height: 70px; padding: 13px 14px; resize: vertical; line-height: 1.6; }
input:focus, textarea:focus { border-color: rgba(37, 99, 235, .55); background: #fff; box-shadow: 0 0 0 3px rgba(37,99,235,.08); }
.button { border: 1px solid var(--quiz-line); border-radius: var(--radius-control); padding: 10px 13px; background: transparent; color: var(--quiz-muted); font-weight: 500; transition: var(--motion-fast) ease; }
.button:hover { border-color: var(--quiz-line-strong); color: var(--quiz-text); background: rgba(17,24,39,.045); }
.button-primary { border-color: #111827; background: #111827; color: #fff; }
.button-primary:hover { border-color: #2563eb; background: #2563eb; color: #fff; }
.button-quiet { color: var(--quiz-faint); }
.theme-toggle { min-width: 58px; }
.setup-theme-toggle { position: absolute; top: 18px; right: 0; }
.form-error { min-height: 20px; margin: 12px 0 0; color: var(--quiz-error); font-size: 12px; }

.study-header { display: flex; align-items: flex-end; justify-content: space-between; gap: var(--space-6); min-height: 126px; padding-bottom: 28px; border-bottom: 1px solid var(--quiz-line); transition: min-height var(--motion-standard) ease, padding var(--motion-standard) ease; }
.back-link { display: inline-block; margin-bottom: 26px; color: var(--quiz-faint); font-size: 12px; text-decoration: none; }
.back-link:hover { color: var(--quiz-accent-strong); }
.study-header h1 { font-size: clamp(27px, 4vw, 45px); }
.header-copy { max-width: 620px; margin: 14px 0 0; color: var(--quiz-muted); font-size: 13px; line-height: 1.75; }
.header-actions { display: flex; align-items: center; gap: 8px; padding-bottom: 4px; }
.quota { margin-right: 12px; color: var(--quiz-faint); font-size: 11px; }
.workspace-heading { display: none; min-width: 0; }
.workspace-heading .eyebrow { margin-bottom: 7px; }
.workspace-heading h2 { max-width: min(760px, 62vw); margin: 0; overflow: hidden; color: var(--quiz-text); font-size: clamp(21px, 2.2vw, 28px); font-weight: 600; letter-spacing: -.02em; line-height: 1.2; text-overflow: ellipsis; white-space: nowrap; }
.workspace-meta { margin: 7px 0 0; color: var(--quiz-faint); font-size: var(--font-label); }
.study-app.has-tree .study-header { min-height: 72px; align-items: center; padding-bottom: 16px; }
.study-app.has-tree .header-intro { display: none; }
.study-app.has-tree .workspace-heading { display: block; }
.study-app.has-tree .header-actions { padding-bottom: 0; }

.study-layout { display: grid; grid-template-columns: 190px minmax(0, 1fr) 420px; gap: 28px; padding-top: 24px; align-items: start; }
.session-rail { min-width: 0; padding-top: 4px; }
.rail-heading { display: flex; justify-content: space-between; align-items: center; color: var(--quiz-text); font-size: 12px; font-weight: 600; letter-spacing: .02em; }
.rail-count { display: grid; place-items: center; min-width: 24px; height: 24px; border: 1px solid var(--quiz-line); border-radius: 50%; color: var(--quiz-accent); font-size: 11px; }
.rail-legend { display: grid; gap: 10px; margin-top: 34px; color: var(--quiz-faint); font-size: 11px; }
.rail-legend span { display: flex; align-items: center; gap: 8px; }
.legend-dot { width: 7px; height: 7px; border-radius: 50%; background: var(--quiz-faint); }
.legend-dot.check { background: var(--quiz-check); }
.legend-dot.followup { background: var(--quiz-followup); }
.legend-dot.custom { background: var(--quiz-custom); }
.history-panel { margin-top: 30px; padding-top: 18px; border-top: 1px solid var(--quiz-line); }
.history-heading { display: flex; align-items: center; justify-content: space-between; gap: 6px; color: var(--quiz-text); font-size: 11px; font-weight: 600; letter-spacing: .02em; }
.history-heading .text-button { padding: 0; font-size: 10px; }
.session-list { display: grid; gap: 15px; max-height: 290px; margin-top: 12px; padding-right: 3px; overflow: auto; }
.history-empty { color: var(--quiz-faint); font-size: 10px; line-height: 1.6; }
.session-group { position: relative; display: grid; gap: 5px; }
.session-group-heading { display: flex; align-items: center; justify-content: space-between; padding: 0 4px 3px 14px; color: var(--quiz-faint); font-size: 10px; font-weight: 500; letter-spacing: .02em; }
.session-group-heading span:last-child { min-width: 18px; text-align: center; letter-spacing: 0; }
.session-item-shell { position: relative; min-width: 0; }
.session-item { position: relative; display: grid; width: 100%; grid-template-columns: 8px minmax(0,1fr); gap: 8px; padding: 9px 8px 9px 5px; border: 1px solid transparent; border-radius: 11px; background: rgba(255,255,255,.55); color: var(--quiz-muted); text-align: left; }
.session-item-marker { position: relative; align-self: stretch; width: 8px; }
.session-item-marker::before { content: ""; position: absolute; left: 3px; top: 8px; width: 5px; height: 5px; border-radius: 50%; background: #b8bbc1; box-shadow: 0 0 0 3px var(--quiz-bg); }
.session-item-marker::after { content: ""; position: absolute; left: 5px; top: 16px; bottom: -15px; width: 1px; background: var(--quiz-line); }
.session-group .session-item-shell:last-child .session-item-marker::after { display: none; }
.session-item-content { min-width: 0; }
.session-item:hover { border-color: var(--quiz-line-strong); background: #fff; color: var(--quiz-text); }
.session-item.is-active { border-color: rgba(37,99,235,.35); background: rgba(37,99,235,.075); color: var(--quiz-text); }
.session-item-shell.is-active .session-item { padding-right: 35px; }
.session-item.is-active .session-item-marker::before { background: var(--quiz-accent); box-shadow: 0 0 0 3px rgba(37,99,235,.12); }
.session-delete-button { position: absolute; z-index: 2; top: 7px; right: 7px; display: grid; place-items: center; width: 24px; height: 24px; box-sizing: border-box; padding: 0; border: 1px solid var(--quiz-line); border-radius: 8px; background: var(--quiz-surface-muted); color: var(--quiz-faint); font-size: 0; opacity: .82; }
.session-delete-button > span { position: relative; display: block; width: 12px; height: 12px; transform: none; }
.session-delete-button > span::before,
.session-delete-button > span::after { content: ""; position: absolute; left: 50%; top: 50%; width: 13px; height: 1.5px; border-radius: 999px; background: currentColor; transform: translate(-50%, -50%) rotate(45deg); }
.session-delete-button > span::after { transform: translate(-50%, -50%) rotate(-45deg); }
.session-delete-button:hover, .session-delete-button:focus-visible { border-color: rgba(225,29,72,.25); background: rgba(225,29,72,.08); color: #e11d48; opacity: 1; outline: 0; }
.session-item.is-draft { border-style: dashed; background: rgba(255,255,255,.3); }
.session-item.is-draft .session-item-marker::before { background: transparent; border: 1px solid #aeb2ba; }
.session-item-title { display: block; overflow: hidden; font-size: 11px; font-weight: 500; line-height: 1.45; text-overflow: ellipsis; white-space: nowrap; }
.session-item-meta { display: flex; justify-content: space-between; gap: 7px; margin-top: 4px; color: var(--quiz-faint); font-size: 9px; }
.bulk-visibility-controls { display: flex; gap: 10px; margin-top: 18px; padding-top: 14px; border-top: 1px solid var(--quiz-line); }
.bulk-visibility-controls .text-button { padding: 0; color: var(--quiz-muted); font-size: 10px; }
.bulk-visibility-controls .text-button:hover:not(:disabled) { color: var(--quiz-accent-strong); }

.conversation-area { min-width: 0; }
.reader-panel { position: sticky; top: 24px; min-width: 0; min-height: 560px; height: min(70vh, 800px); padding: 18px 18px 16px; border: 1px solid var(--quiz-line); border-radius: var(--radius-panel); background: linear-gradient(150deg, #fff, #fafaf8); box-shadow: var(--shadow-panel); overflow: auto; }
.reader-empty { min-height: 370px; display: grid; place-content: center; text-align: center; color: var(--quiz-muted); }
.reader-empty-mark { display: block; margin-bottom: 16px; color: var(--quiz-accent); font-size: 32px; }
.reader-empty h2 { margin: 0 0 8px; color: var(--quiz-text); font-size: 16px; font-weight: 500; }
.reader-empty p { margin: 0; font-size: 12px; line-height: 1.75; }
.reader-view { min-height: 470px; display: flex; flex-direction: column; transform-origin: 50% 0; }
.reader-view.is-refreshing { animation: inspector-refresh 220ms var(--ease-standard); }
.reader-header { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding-bottom: 14px; border-bottom: 1px solid var(--quiz-line); color: var(--quiz-muted); font-size: 11px; }
.reader-role { color: var(--quiz-accent-strong); }
.reader-branch { margin-left: 9px; color: var(--quiz-check); }
.reader-depth { color: var(--quiz-faint); font-size: 10px; }
.reader-content { flex: 1; padding-top: 20px; color: var(--quiz-text); font-size: 16px; line-height: 1.75; white-space: pre-wrap; overflow-wrap: anywhere; }
.reader-concealed { flex: 1; display: grid; align-content: center; justify-items: start; gap: 12px; min-height: 250px; color: var(--quiz-muted); }
.reader-concealed-label { display: none; }
.reader-concealed-summary { max-width: 360px; color: var(--quiz-accent-strong); font-size: 16px; line-height: 1.8; }
.reader-footer { display: flex; align-items: center; justify-content: space-between; gap: 10px; margin-top: 20px; padding-top: 13px; border-top: 1px solid var(--quiz-line); color: var(--quiz-faint); font-size: 10px; }
.reader-context { display: grid; gap: 13px; margin-top: 22px; padding-top: 16px; border-top: 1px solid var(--quiz-line); }
.reader-context-grid { display: grid; grid-template-columns: minmax(0, 1.5fr) minmax(86px, .5fr); gap: 10px; }
.reader-context-block { min-width: 0; padding: 11px 12px; border: 1px solid var(--quiz-line); border-radius: 12px; background: rgba(17,24,39,.025); }
.reader-context-label { display: block; margin-bottom: 6px; color: var(--quiz-faint); font-size: 10px; font-weight: 500; letter-spacing: .02em; }
.reader-context-block p { margin: 0; overflow: hidden; color: var(--quiz-muted); font-size: 11px; line-height: 1.55; text-overflow: ellipsis; }
.reader-context-actions { display: flex; flex-wrap: wrap; gap: 7px; }
.reader-context-actions .text-button { padding: 7px 9px; border: 1px solid var(--quiz-line); border-radius: 9px; background: rgba(255,255,255,.7); }
.context-strip { display: flex; align-items: center; gap: 9px; min-height: 30px; margin-bottom: 12px; color: var(--quiz-muted); font-size: 12px; }
.context-label { color: var(--quiz-faint); font-size: 10px; font-weight: 500; letter-spacing: .02em; }
.graph-toolbar { display: flex; align-items: center; gap: 5px; margin-left: auto; }
.view-switch { display: inline-flex; align-items: center; padding: 3px; border: 1px solid var(--quiz-line); border-radius: 10px; background: rgba(255,255,255,.7); }
.view-option { padding: 5px 8px; border: 0; border-radius: 7px; background: transparent; color: var(--quiz-faint); font-size: 11px; font-weight: 500; }
.view-option:hover { color: var(--quiz-text); }
.view-option.is-selected { background: #111827; color: #fff; box-shadow: 0 3px 10px rgba(17,24,39,.16); }
.graph-toolbar > span { width: 42px; color: var(--quiz-faint); font-size: 10px; text-align: right; }
.icon-button { width: 27px; height: 27px; border: 1px solid var(--quiz-line); border-radius: 8px; background: transparent; color: var(--quiz-muted); }
.icon-button:hover { border-color: var(--quiz-line-strong); color: var(--quiz-text); }
.text-button { border: 0; background: transparent; color: var(--quiz-faint); font-size: 11px; font-weight: 500; }
.text-button:hover { color: var(--quiz-accent-strong); }
.canvas-undo-button { min-height: 27px; padding: 4px 8px; border: 1px solid var(--quiz-line); border-radius: 8px; }
.canvas-undo-button:hover:not(:disabled) { border-color: var(--quiz-line-strong); background: var(--quiz-surface-muted); }
.export-control { display: inline-flex; align-items: center; gap: 4px; }
.export-control select { max-width: 118px; padding: 5px 6px; border: 1px solid var(--quiz-line); border-radius: 7px; background: var(--quiz-surface); color: var(--quiz-muted); font-size: 10px; }

.graph-viewport { position: relative; min-height: 560px; height: min(70vh, 800px); overflow: hidden; border: 1px solid var(--quiz-line); border-radius: var(--radius-panel); background-color: #fafaf8; background-image: radial-gradient(rgba(17,24,39,.13) .7px, transparent .7px); background-size: 22px 22px; box-shadow: inset 0 0 70px rgba(17,24,39,.035), 0 12px 34px rgba(17,24,39,.045); outline: none; cursor: grab; }
.graph-viewport:focus-visible { border-color: rgba(37,99,235,.48); box-shadow: 0 0 0 3px rgba(37,99,235,.08); }
.graph-viewport.is-panning { cursor: grabbing; }
.graph-world { position: absolute; left: 0; top: 0; width: 1px; height: 1px; transform-origin: 0 0; will-change: transform; user-select: none; -webkit-user-select: none; }
.graph-edges { position: absolute; left: 0; top: 0; z-index: 1; width: 100%; height: 100%; overflow: visible; pointer-events: none; }
.graph-edge { fill: none; stroke: #111827; stroke-width: 3.2; stroke-linecap: round; vector-effect: non-scaling-stroke; filter: url(#edge-glow); opacity: .9; }
.graph-viewport.is-view-transitioning .graph-edge { animation: edge-reveal 300ms var(--ease-standard) both; }
.graph-edge.question { stroke: #111827; }
.graph-edge.followup { stroke: var(--quiz-followup); }
.graph-edge.check { stroke: var(--quiz-check); }
.graph-edge.custom { stroke: var(--quiz-custom); }
.graph-nodes { position: absolute; left: 0; top: 0; z-index: 2; }
.graph-node { position: absolute; width: 300px; transform: translate(-50%, -50%); transition: left var(--motion-standard) var(--ease-standard), top var(--motion-standard) var(--ease-standard), width var(--motion-standard) var(--ease-standard), opacity var(--motion-standard) ease, filter var(--motion-standard) ease, transform var(--motion-standard) var(--ease-standard); animation: node-arrive var(--motion-standard) var(--ease-standard) both; z-index: 2; }
.graph-node.is-view-hidden { opacity: 0; filter: blur(2px); transform: translate(-50%, -50%) scale(.965); pointer-events: none; }
.graph-node.is-current { z-index: 4; }
.graph-node.is-path { opacity: .94; }
.graph-node.is-nearby { opacity: .74; }
.graph-node.is-nearby .node-card { border-style: dashed; box-shadow: 0 9px 24px rgba(17,24,39,.055); }
.graph-node.is-nearby .node-summary { -webkit-line-clamp: 1; }
.graph-node.is-nearby .branch-slots { opacity: 0; pointer-events: none; }
.graph-node.is-nearby:hover,
.graph-node.is-nearby:focus-within { opacity: .94; }
.graph-node.is-background { opacity: .66; }
.graph-node.is-background .node-card { border-color: rgba(17,24,39,.075); box-shadow: 0 9px 24px rgba(17,24,39,.055); }
.graph-node.is-background .node-summary { -webkit-line-clamp: 1; }
.graph-node.is-background .branch-slots { opacity: 0; pointer-events: none; }
.graph-node.is-background:hover { opacity: .9; }
.graph-node.is-background:hover .branch-slots,
.graph-node.is-background:focus-within .branch-slots { opacity: 1; pointer-events: auto; }
.graph-node.assistant:hover,
.graph-node.assistant:focus-within,
.graph-node.assistant.is-drawer-open { z-index: 12; }
.graph-node.is-current { width: 340px; opacity: 1; }
.graph-node.is-current .node-summary { color: var(--quiz-text); font-size: 15px; -webkit-line-clamp: 4; }
.study-app.is-large-tree .graph-node { animation: none; transition-duration: .01ms; }
.study-app.is-large-tree .node-card { box-shadow: 0 8px 22px rgba(17,24,39,.07); }
.study-app.is-large-tree .graph-node.is-background .branch-slots { display: none; }
.node-card { position: relative; display: flex; flex-direction: column; min-width: 220px; min-height: 90px; border: 1px solid var(--quiz-line); border-radius: var(--radius-card); background: rgba(255,255,255,.98); box-shadow: var(--shadow-card); overflow: hidden; cursor: grab; }
.node-card.is-node-dragging, .node-card.is-node-resizing { cursor: grabbing; transition: none; }
.graph-node.user .node-card { border-color: rgba(17,24,39,.14); background: var(--quiz-user); }
.graph-node.is-current .node-card { border-color: rgba(37,99,235,.72); box-shadow: 0 0 0 3px rgba(37,99,235,.1), 0 20px 46px rgba(17,24,39,.14); }
.graph-node.is-current:not(.is-folded) .node-card { transform: translateY(-2px); }
.node-header { display: flex; flex: 0 0 auto; align-items: center; justify-content: space-between; gap: 10px; padding: 11px 14px 0; color: var(--quiz-faint); font-size: 11px; font-weight: 500; letter-spacing: .02em; }
.node-branch { color: var(--quiz-accent); letter-spacing: 0; text-transform: none; }
.graph-node[data-branch="check"] .node-branch { color: var(--quiz-check); }
.graph-node[data-branch="custom"] .node-branch { color: var(--quiz-custom); }
.node-body { flex: 1 1 auto; min-height: 0; display: flex; flex-direction: column; overflow: hidden; }
.node-content { display: block; flex: 1 1 auto; min-height: 0; max-height: none; overflow: hidden; overscroll-behavior: contain; padding: 10px 14px 13px; color: var(--quiz-text); font-size: 15px; line-height: 1.7; white-space: pre-wrap; overflow-wrap: anywhere; scrollbar-width: thin; scrollbar-color: transparent transparent; }
.node-content::-webkit-scrollbar { width: 8px; }
.node-content::-webkit-scrollbar-track { background: transparent; }
.node-content::-webkit-scrollbar-thumb { border: 2px solid transparent; border-radius: 999px; background: transparent; background-clip: padding-box; transition: background-color var(--motion-fast) ease; }
.graph-node.is-current .node-content { overflow-y: auto; }
.graph-node.is-current .node-content:hover { scrollbar-color: rgba(17,24,39,.32) transparent; }
.graph-node.is-current .node-content:hover::-webkit-scrollbar-thumb { background-color: rgba(17,24,39,.32); }
.graph-node.is-current .node-content:hover::-webkit-scrollbar-thumb:hover { background-color: rgba(17,24,39,.5); }
.node-summary { display: none; flex: 1 1 auto; min-height: 0; padding: 8px 14px 10px; color: var(--quiz-muted); font-size: 15px; line-height: 1.55; overflow: hidden; text-overflow: ellipsis; }
.node-actions { display: flex; flex: 0 0 auto; align-items: center; gap: 10px; min-height: 33px; padding: 6px 25px 6px 13px; border-top: 1px solid rgba(17,24,39,.065); background: linear-gradient(180deg, rgba(248,249,251,.4), rgba(248,249,251,.78)); }
.node-action { min-height: 20px; padding: 0; border: 0; background: transparent; color: var(--quiz-faint); font-size: 11px; font-weight: 500; }
.node-action-continue { margin-right: auto; }
.node-action-drawer { display: none; }
.node-action:hover { color: var(--quiz-accent-strong); }
.node-action-delete { position: absolute; top: 8px; right: 8px; z-index: 4; display: inline-flex; align-items: center; justify-content: center; width: 22px; height: 22px; padding: 0; border: 1px solid rgba(220,38,38,.35); border-radius: 50%; background: rgba(220,38,38,.08); color: #dc2626; cursor: pointer; }
.node-action-delete::before, .node-action-delete::after { content: ""; position: absolute; left: 50%; top: 50%; width: 11px; height: 2px; border-radius: 999px; background: currentColor; transform: translate(-50%, -50%) rotate(45deg); }
.node-action-delete::after { transform: translate(-50%, -50%) rotate(-45deg); }
.node-action-delete:hover { border-color: #ff9c9c; background: #9b2b38; color: #fff; box-shadow: 0 0 14px rgba(255, 91, 105, .45); }
.graph-node.user .node-header { padding-right: 42px; }
.branch-slots { position: absolute; left: 10px; right: 10px; top: calc(100% + 7px); z-index: 8; display: grid; grid-template-columns: repeat(3, minmax(0, 1fr)); gap: 5px; padding: 7px; border: 1px solid rgba(17,24,39,.12); border-radius: 12px; background: rgba(255,255,255,.96); box-shadow: 0 18px 42px rgba(17,24,39,.16); opacity: 0; visibility: hidden; pointer-events: none; transform: translateY(-10px) scale(.975); transform-origin: 50% 0; transition: opacity var(--motion-fast) ease, transform var(--motion-standard) var(--ease-emphasis), visibility 0s linear var(--motion-fast); backdrop-filter: blur(14px); }
.branch-slots::before { content: ""; position: absolute; left: 0; right: 0; top: -8px; height: 8px; }
.graph-node.assistant:hover .branch-slots,
.graph-node.assistant:focus-within .branch-slots,
.graph-node.assistant.is-drawer-open .branch-slots { opacity: 1; visibility: visible; pointer-events: auto; transform: translateY(0) scale(1); transition-delay: 0s; }
.branch-slot { min-width: 0; min-height: 31px; padding: 7px 5px; border: 1px solid var(--quiz-line); border-radius: 8px; background: rgba(17,24,39,.018); color: var(--quiz-muted); font-size: 11px; font-weight: 500; white-space: nowrap; overflow: hidden; text-overflow: ellipsis; }
.branch-slot:hover:not(:disabled), .branch-slot:focus-visible:not(:disabled) { border-color: var(--quiz-line-strong); color: var(--quiz-text); background: rgba(17,24,39,.05); outline: 0; }
.branch-slot.check { border-color: rgba(245,158,11,.4); }
.branch-slot.followup { border-color: rgba(14,165,233,.35); }
.branch-slot.custom { border-color: rgba(168,85,247,.35); }
.branch-slot.is-used { color: var(--quiz-faint); text-decoration: line-through; opacity: .55; }
.node-branch-marker { display: inline-block; width: 6px; height: 6px; margin-right: 5px; border-radius: 50%; background: var(--quiz-faint); }
.node-branch-marker.check { background: var(--quiz-check); }
.node-branch-marker.custom { background: var(--quiz-custom); }

.node-conceal-overlay { position: absolute; inset: 0; z-index: 5; display: grid; place-content: center; justify-items: center; gap: 8px; padding: 18px; border-radius: inherit; background: rgba(255,255,255,.86); backdrop-filter: blur(12px) saturate(1.2); text-align: center; }
.graph-node.is-concealed .node-card > :not(.node-conceal-overlay) { visibility: hidden; }
.graph-node.is-concealed .branch-slots { display: none; }
.node-conceal-summary { max-width: 250px; color: var(--quiz-text); font-size: 14px; font-weight: 600; line-height: 1.7; }
.node-conceal-summary.question { color: #111827; }
.node-conceal-summary.followup { color: var(--quiz-followup); }
.node-conceal-summary.check { color: var(--quiz-check); }
.node-conceal-summary.custom { color: var(--quiz-custom); }
.node-conceal-reveal { padding: 7px 16px; border: 1px solid currentColor; border-radius: 999px; background: rgba(17,24,39,.035); color: var(--quiz-text); font-size: 11px; }
.node-conceal-reveal:hover { background: #111827; color: #fff; }
.node-resize-handle { position: absolute; right: 3px; bottom: 3px; z-index: 7; width: 15px; height: 15px; cursor: nwse-resize; opacity: .48; }
.node-resize-handle::after { content: ""; position: absolute; right: 1px; bottom: 1px; width: 8px; height: 8px; border-right: 2px solid var(--quiz-accent); border-bottom: 2px solid var(--quiz-accent); }
.node-resize-handle:hover { opacity: 1; }

.loading-node, .inline-error { position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%); z-index: 5; padding: 13px 16px; border: 1px solid var(--quiz-line); border-radius: 12px; background: rgba(255,255,255,.97); color: var(--quiz-muted); font-size: 12px; white-space: nowrap; box-shadow: 0 16px 34px rgba(17,24,39,.12); }
.loading-node::after { content: ""; display: inline-block; width: 5px; height: 5px; margin-left: 7px; border-radius: 50%; background: var(--quiz-accent); animation: pulse 1s infinite alternate; }
.inline-error { border-color: rgba(201, 148, 148, .3); color: var(--quiz-error); white-space: normal; }
@keyframes pulse { from { opacity: .25; } to { opacity: 1; } }
.empty-state { position: absolute; inset: 0; display: grid; place-content: center; padding: 28px; text-align: center; color: var(--quiz-muted); pointer-events: none; }
.empty-mark { display: block; margin-bottom: 14px; color: var(--quiz-accent); font-size: 30px; }
.empty-state h2 { margin: 0 0 8px; color: var(--quiz-text); font-size: 15px; font-weight: 500; }
.empty-state p { max-width: 380px; margin: 0 auto; font-size: 12px; line-height: 1.7; }

.minimap { position: absolute; right: 14px; top: 14px; bottom: auto; z-index: 6; width: 190px; height: 142px; padding: 8px; border: 1px solid var(--quiz-line); border-radius: 12px; background: rgba(255,255,255,.88); box-shadow: 0 12px 30px rgba(17,24,39,.1); backdrop-filter: blur(10px); }
.minimap-title { margin: 0 0 4px 2px; color: var(--quiz-faint); font-size: 8px; letter-spacing: .15em; }
#minimap-svg { display: block; width: 100%; height: calc(100% - 16px); overflow: visible; }
.mini-edge { fill: none; stroke: #111827; stroke-width: 2.6; stroke-linecap: round; filter: url(#mini-edge-glow); opacity: .9; }
.mini-edge.question { stroke: #111827; }
.mini-edge.followup { stroke: var(--quiz-followup); }
.mini-edge.check { stroke: var(--quiz-check); }
.mini-edge.custom { stroke: var(--quiz-custom); }
.mini-node { fill: rgba(17,24,39,.55); }
.mini-node.user { fill: rgba(17,24,39,.85); }
.mini-node.check { fill: var(--quiz-check); }
.mini-node.custom { fill: var(--quiz-custom); }
.mini-viewport { fill: rgba(37,99,235,.06); stroke: rgba(37,99,235,.7); stroke-width: 1; pointer-events: none; }

.composer { position: relative; z-index: 8; margin-top: 14px; padding: 12px; border: 1px solid var(--quiz-line-strong); border-radius: var(--radius-card); background: rgba(255,255,255,.94); box-shadow: 0 18px 45px rgba(17,24,39,.09); backdrop-filter: blur(15px); }
.composer-tools { display: flex; flex-wrap: wrap; gap: 6px; margin-bottom: 9px; }
.suggestion { padding: 6px 9px; border: 1px solid var(--quiz-line); border-radius: 999px; background: transparent; color: var(--quiz-muted); font-size: 11px; font-weight: 500; }
.suggestion:hover, .suggestion.is-selected { border-color: rgba(37,99,235,.35); color: var(--quiz-accent-strong); background: rgba(37,99,235,.07); }
.composer-form { display: flex; flex-direction: column; gap: 8px; }
.composer-footer { display: flex; justify-content: space-between; align-items: center; gap: 10px; color: var(--quiz-faint); font-size: 11px; }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0; }

/* ── 奏折式折叠 / 扑克牌堆叠 ── */
.node-card { transition: transform var(--motion-emphasis) var(--ease-emphasis), border-color var(--motion-fast) ease, box-shadow var(--motion-standard) ease, background var(--motion-fast) ease; }
.graph-node.is-folded { z-index: 1; pointer-events: none; }  /* 折叠卡只做视觉，不拦截点击 */
.graph-node.is-folded .node-actions,
.graph-node.is-folded .branch-slots,
.graph-node.is-folded .node-content { display: none; }
.graph-node.is-folded .node-header { padding-bottom: 11px; }
.graph-node.is-fold-root { z-index: 5; }  /* 父节点恒在牌堆之上，按钮可点 */
.graph-node.is-fold-root .node-card { border-color: rgba(37,99,235,.58); box-shadow: 0 18px 46px rgba(17,24,39,.16); }
.graph-node.is-fold-root:not(.is-view-hidden) .node-card { animation: deck-anchor 420ms var(--ease-emphasis); }

/* ── 2026 workspace rhythm: the canvas is the visual centre ── */
.quiz-shell { width: min(1720px, 100%); padding: 30px 36px 38px; }
.eyebrow { margin-bottom: 10px; font-size: 11px; letter-spacing: .13em; }
.study-header { min-height: 112px; gap: 24px; padding-bottom: 20px; }
.study-header h1 { font-size: clamp(34px, 3.35vw, 46px); }
.header-copy { max-width: 680px; margin-top: 11px; font-size: 14px; line-height: 1.62; }
.quota { font-size: 12px; }
.button { font-size: 13px; }

.workspace-panel-switcher { display: none; }
.panel-backdrop { position: fixed; inset: 0; z-index: 24; width: 100%; border: 0; background: rgba(17,24,39,.2); backdrop-filter: blur(3px); }
.study-layout {
  --workspace-height: clamp(550px, calc(100dvh - 170px), 820px);
  grid-template-columns: 220px minmax(520px, 1fr) 390px;
  gap: 22px;
  align-items: stretch;
  padding-top: 20px;
}
.session-rail { display: flex; min-height: 0; height: var(--workspace-height); flex-direction: column; padding-top: 5px; }
.rail-heading { font-size: 13px; letter-spacing: .02em; }
.rail-legend { font-size: 12px; }
.rail-legend { display: flex; flex-wrap: wrap; gap: 10px 15px; margin-top: 20px; }
.history-panel { display: flex; min-height: 0; flex: 1; flex-direction: column; margin-top: 22px; padding-top: 16px; }
.history-heading { font-size: 12px; letter-spacing: .02em; }
.history-heading .text-button, .bulk-visibility-controls .text-button { font-size: 11px; }
.session-list { min-width: 0; max-height: none; flex: 1; overflow-x: hidden; }
.session-item { min-width: 0; padding: 10px; }
.session-item-title { display: -webkit-box; font-size: 13px; line-height: 1.4; white-space: normal; -webkit-box-orient: vertical; -webkit-line-clamp: 2; }
.session-item-meta { font-size: 11px; }
.history-empty { font-size: 12px; }
.bulk-visibility-controls { margin-top: 12px; padding-top: 12px; }

.conversation-area { position: relative; display: grid; min-height: 0; height: var(--workspace-height); grid-template-rows: auto minmax(0, 1fr); }
.context-strip { display: grid; grid-template-columns: auto minmax(0, 1fr) auto; gap: 7px 10px; min-height: 38px; margin-bottom: 10px; font-size: 13px; }
.context-label { font-size: 11px; letter-spacing: .02em; white-space: nowrap; }
#context-label { min-width: 0; overflow: hidden; text-overflow: ellipsis; white-space: nowrap; }
.graph-toolbar { min-width: 0; margin-left: 0; }
.graph-toolbar > span { font-size: 11px; }
.icon-button { width: 30px; height: 30px; font-size: 13px; }
.text-button { font-size: 12px; }
.export-control select { font-size: 11px; }

.graph-viewport { min-height: 0; height: auto; }
.composer {
  position: absolute;
  left: 50%;
  bottom: 16px;
  width: min(760px, calc(100% - 32px));
  margin: 0;
  padding: 9px;
  border-color: rgba(17,24,39,.18);
  border-radius: 19px;
  box-shadow: 0 22px 60px rgba(17,24,39,.16), 0 2px 10px rgba(17,24,39,.06);
  transform: translateX(-50%);
  transition: width var(--motion-standard) ease, box-shadow var(--motion-standard) ease, border-color var(--motion-fast) ease;
}
.composer:hover, .composer:focus-within { width: min(800px, calc(100% - 24px)); border-color: rgba(37,99,235,.32); box-shadow: 0 26px 74px rgba(17,24,39,.2), 0 0 0 3px rgba(37,99,235,.055); }
.composer-tools { max-height: 0; margin: 0; overflow: hidden; opacity: 0; transform: translateY(5px); transition: max-height var(--motion-standard) ease, margin var(--motion-standard) ease, opacity var(--motion-fast) ease, transform var(--motion-standard) ease; }
.composer:hover .composer-tools, .composer:focus-within .composer-tools { max-height: 38px; margin-bottom: 7px; opacity: 1; transform: translateY(0); }
.suggestion { padding: 6px 10px; font-size: 12px; }
.composer textarea { min-height: 46px; max-height: 46px; padding-block: 10px; resize: none; font-size: 15px; transition: min-height var(--motion-standard) ease, max-height var(--motion-standard) ease, border-color var(--motion-fast) ease, box-shadow var(--motion-fast) ease; }
.composer:focus-within textarea { min-height: 74px; max-height: 110px; resize: vertical; }
.composer-footer { font-size: 12px; }

.reader-panel { top: 20px; min-height: 0; height: var(--workspace-height); padding: 20px; }
.reader-empty { min-height: calc(100% - 46px); }
.reader-empty h2 { font-size: 20px; }
.reader-empty p { font-size: 13px; }
.reader-view { min-height: calc(100% - 46px); }
.reader-header { font-size: 12px; font-weight: 500; }
.reader-depth { font-size: 11px; }
.reader-content { font-size: 16px; line-height: 1.75; }
.reader-footer { font-size: 11px; }

/* At overview scale, interaction chrome disappears and cards become labels. */
.graph-viewport.is-overview .node-actions,
.graph-viewport.is-overview .branch-slots,
.graph-viewport.is-overview .node-resize-handle,
.graph-viewport.is-overview .node-action-delete { display: none; }
.graph-viewport.is-overview .node-content { display: none; }
.graph-viewport.is-overview .node-summary { display: -webkit-box; padding-block: 8px 11px; font-size: 12px; -webkit-box-orient: vertical; -webkit-line-clamp: 1; }
.graph-viewport.is-overview .node-header { padding-bottom: 8px; font-size: 11px; }
.graph-viewport.is-overview .node-card { min-height: 76px; }

@media (max-width: 1439px) and (min-width: 1360px) {
  .quiz-shell { padding-inline: 28px; }
  .study-layout { grid-template-columns: 190px minmax(440px, 1fr) 350px; gap: 18px; }
  .context-strip { grid-template-columns: auto minmax(0, 1fr); }
  .graph-toolbar { grid-column: 1 / -1; justify-content: flex-end; }
}

@media (max-width: 1359px) {
  .quiz-shell { padding-inline: 24px; }
  .workspace-panel-switcher { display: flex; justify-content: flex-end; gap: 8px; margin-top: 12px; }
  .panel-toggle { padding-block: 8px; background: rgba(255,255,255,.68); }
  .panel-toggle[aria-expanded="true"] { border-color: rgba(37,99,235,.35); background: rgba(37,99,235,.08); color: var(--quiz-accent-strong); }
  .study-app:has(.workspace-panel-switcher) .study-layout { grid-template-columns: minmax(0, 1fr); padding-top: 12px; }
  .study-app:has(.workspace-panel-switcher) .conversation-area { grid-column: 1; }
  .study-app:has(.workspace-panel-switcher) .session-rail,
  .study-app:has(.workspace-panel-switcher) .reader-panel {
    position: fixed;
    left: 50%;
    right: auto;
    top: auto;
    bottom: 12px;
    z-index: 30;
    width: min(430px, calc(100vw - 24px));
    max-height: calc(100dvh - 72px);
    padding: 20px;
    border: 1px solid var(--quiz-line);
    border-radius: 22px;
    background: var(--quiz-surface);
    box-shadow: 0 28px 80px rgba(17,24,39,.22);
    opacity: 0;
    overflow: auto;
    pointer-events: none;
    transform: translate(-50%, calc(100% + 28px));
    transition: transform var(--motion-standard) var(--ease-emphasis), opacity var(--motion-fast) ease;
  }
  .study-app:has(.workspace-panel-switcher) .session-rail.is-panel-open,
  .study-app:has(.workspace-panel-switcher) .reader-panel.is-panel-open { opacity: 1; pointer-events: auto; transform: translate(-50%, 0); }
  .study-app:has(.workspace-panel-switcher) .session-rail { height: min(680px, calc(100dvh - 72px)); }
  .study-app:has(.workspace-panel-switcher) .reader-panel { height: min(760px, calc(100dvh - 72px)); min-height: 0; margin: 0; }
  .study-app:has(.workspace-panel-switcher) .history-panel { min-height: 250px; }
  body.has-open-workspace-panel { overflow: hidden; }
  .context-strip { grid-template-columns: auto minmax(0, 1fr); }
  .graph-toolbar { grid-column: 1 / -1; justify-content: flex-end; }
}

@media (max-width: 860px) {
  .quiz-shell { padding: 22px 15px 30px; }
  .study-header { min-height: 0; align-items: flex-start; flex-direction: column; gap: 13px; padding-bottom: 16px; }
  .study-header h1 { font-size: clamp(28px, 8vw, 34px); line-height: 1.12; }
  .header-copy { margin-top: 9px; font-size: 13px; line-height: 1.55; }
  .eyebrow { margin-bottom: 8px; font-size: 10px; }
  .header-actions { width: 100%; flex-wrap: wrap; padding: 0; }
  .quota { margin-right: auto; }
  .workspace-panel-switcher { margin-top: 10px; }
  .study-layout { --workspace-height: auto; display: block; padding-top: 10px; }
  .conversation-area { display: grid; height: auto; grid-template-rows: auto minmax(470px, 66dvh) auto; }
  .context-strip { grid-template-columns: auto minmax(0, 1fr); min-height: 68px; margin-bottom: 8px; }
  .graph-toolbar { width: 100%; justify-content: flex-start; overflow-x: auto; padding: 0 16px 2px 0; scrollbar-width: none; -ms-overflow-style: none; mask-image: linear-gradient(to right, #000 0, #000 calc(100% - 18px), transparent 100%); }
  .graph-toolbar::-webkit-scrollbar { display: none; }
  .graph-toolbar > * { flex: 0 0 auto; }
  .graph-toolbar .text-button { min-height: 32px; padding-inline: 8px; white-space: nowrap; }
  .view-switch { flex: 0 0 auto; }
  .view-option { min-height: 32px; padding: 6px 9px; }
  .icon-button { width: 32px; height: 32px; }
  .export-control { margin-left: 0; }
  .export-control select { max-width: 104px; }
  .graph-viewport { min-height: 470px; }
  .composer { position: relative; left: auto; bottom: auto; width: 100%; margin-top: 10px; padding: 10px; transform: none; }
  .composer:hover, .composer:focus-within { width: 100%; }
  .composer-tools { max-height: none; margin-bottom: 7px; opacity: 1; overflow: visible; transform: none; }
  .composer textarea, .composer:focus-within textarea { min-height: 64px; max-height: 108px; resize: vertical; }
  .reader-panel-toggle { display: inline-flex; }
  .reader-empty, .reader-view { min-height: 280px; }
  .node-action-drawer { display: inline-flex; align-items: center; }
}

@media (max-width: 560px) {
  .study-app.has-tree .workspace-heading .eyebrow { display: none; }
  .study-header h1 { max-width: 340px; font-size: 30px; }
  .header-copy { max-width: 340px; }
  .header-actions .button { padding: 8px 10px; }
  .workspace-panel-switcher { justify-content: stretch; }
  .workspace-panel-switcher .button { flex: 1; }
  .graph-node { width: 260px; }
  .minimap { right: 9px; top: 9px; bottom: auto; width: 145px; height: 110px; }
  .composer-tools { flex-wrap: nowrap; overflow-x: auto; padding-bottom: 2px; }
  .suggestion { flex: 0 0 auto; }
  .composer-footer { justify-content: flex-end; }
  .composer-footer > span { display: none; }
  .export-control select { display: none; }
  .session-rail, .reader-panel { bottom: 8px; width: calc(100vw - 16px); border-radius: 20px; }
}

html[data-theme="dark"] {
  --quiz-bg: #0b0e13;
  --quiz-surface: #12171e;
  --quiz-surface-raised: #171d25;
  --quiz-user: #181e26;
  --quiz-line: rgba(226,232,240,.12);
  --quiz-line-strong: rgba(226,232,240,.24);
  --quiz-text: #edf2f7;
  --quiz-muted: #aeb7c4;
  --quiz-faint: #818c9b;
  --quiz-accent: #6d97ff;
  --quiz-accent-strong: #dce7ff;
  --quiz-check: #fbbf24;
  --quiz-followup: #38bdf8;
  --quiz-custom: #c084fc;
  --quiz-error: #fb7185;
  --shadow-card: 0 16px 38px rgba(0,0,0,.32);
  --shadow-panel: 0 22px 64px rgba(0,0,0,.34);
}
html[data-theme="dark"] body { background: radial-gradient(circle at 75% -10%, rgba(109,151,255,.11), transparent 34rem), var(--quiz-bg); }
html[data-theme="dark"] input,
html[data-theme="dark"] textarea { background: rgba(23,29,37,.9); color: var(--quiz-text); }
html[data-theme="dark"] input:focus,
html[data-theme="dark"] textarea:focus { background: #171d25; border-color: rgba(109,151,255,.65); }
html[data-theme="dark"] .button:hover { background: rgba(255,255,255,.07); }
html[data-theme="dark"] .button-primary { border-color: #edf2f7; background: #edf2f7; color: #111827; }
html[data-theme="dark"] .button-primary:hover { border-color: #6d97ff; background: #6d97ff; color: #07101f; }
html[data-theme="dark"] .session-item { background: rgba(18,23,30,.62); }
html[data-theme="dark"] .session-item:hover { background: #171d25; }
html[data-theme="dark"] .session-item.is-active { border-color: rgba(109,151,255,.42); background: rgba(109,151,255,.12); }
html[data-theme="dark"] .session-item.is-draft { background: rgba(18,23,30,.38); }
html[data-theme="dark"] .session-delete-button:hover,
html[data-theme="dark"] .session-delete-button:focus-visible { border-color: rgba(251,113,133,.3); background: rgba(251,113,133,.11); color: #fb7185; }
html[data-theme="dark"] .session-delete-button { border-color: rgba(226,232,240,.14); background: rgba(255,255,255,.055); }
html[data-theme="dark"] .reader-panel { background: linear-gradient(150deg, #141a22, #0f141b); }
html[data-theme="dark"] .reader-context-block { background: rgba(255,255,255,.035); }
html[data-theme="dark"] .reader-context-actions .text-button { background: rgba(255,255,255,.04); }
html[data-theme="dark"] .graph-viewport { background-color: #0d1117; background-image: radial-gradient(rgba(226,232,240,.13) .7px, transparent .7px); box-shadow: inset 0 0 80px rgba(0,0,0,.34), 0 14px 36px rgba(0,0,0,.22); }
html[data-theme="dark"] .graph-edge,
html[data-theme="dark"] .graph-edge.question { stroke: #d9e1ea; }
html[data-theme="dark"] .graph-edge.followup { stroke: var(--quiz-followup); }
html[data-theme="dark"] .graph-edge.check { stroke: var(--quiz-check); }
html[data-theme="dark"] .graph-edge.custom { stroke: var(--quiz-custom); }
html[data-theme="dark"] .node-card { background: rgba(18,23,30,.98); }
html[data-theme="dark"] .graph-node.user .node-card { border-color: rgba(226,232,240,.16); background: var(--quiz-user); }
html[data-theme="dark"] .graph-node.is-background .node-card { border-color: rgba(226,232,240,.09); }
html[data-theme="dark"] .node-actions { border-color: rgba(226,232,240,.08); background: linear-gradient(180deg, rgba(255,255,255,.018), rgba(255,255,255,.045)); }
html[data-theme="dark"] .branch-slots { border-color: rgba(226,232,240,.16); background: rgba(18,23,30,.96); box-shadow: 0 18px 46px rgba(0,0,0,.42); }
html[data-theme="dark"] .branch-slot { background: rgba(255,255,255,.025); }
html[data-theme="dark"] .branch-slot:hover:not(:disabled),
html[data-theme="dark"] .branch-slot:focus-visible:not(:disabled) { background: rgba(255,255,255,.08); }
html[data-theme="dark"] .node-conceal-overlay { background: rgba(15,20,27,.88); }
html[data-theme="dark"] .node-conceal-summary.question { color: var(--quiz-text); }
html[data-theme="dark"] .node-conceal-reveal { background: rgba(255,255,255,.04); }
html[data-theme="dark"] .node-conceal-reveal:hover { background: #edf2f7; color: #111827; }
html[data-theme="dark"] .graph-node.is-current .node-content:hover { scrollbar-color: rgba(226,232,240,.38) transparent; }
html[data-theme="dark"] .graph-node.is-current .node-content:hover::-webkit-scrollbar-thumb { background-color: rgba(226,232,240,.38); }
html[data-theme="dark"] .graph-node.is-current .node-content:hover::-webkit-scrollbar-thumb:hover { background-color: rgba(226,232,240,.58); }
html[data-theme="dark"] .view-switch { background: rgba(18,23,30,.76); }
html[data-theme="dark"] .view-option.is-selected { background: #edf2f7; color: #111827; box-shadow: 0 4px 14px rgba(0,0,0,.3); }
html[data-theme="dark"] .export-control select { background: var(--quiz-surface); }
html[data-theme="dark"] .minimap { background: rgba(18,23,30,.9); box-shadow: 0 14px 34px rgba(0,0,0,.34); }
html[data-theme="dark"] .mini-edge { stroke: #d9e1ea; }
html[data-theme="dark"] .mini-edge.followup { stroke: var(--quiz-followup); }
html[data-theme="dark"] .mini-edge.check { stroke: var(--quiz-check); }
html[data-theme="dark"] .mini-edge.custom { stroke: var(--quiz-custom); }
html[data-theme="dark"] .mini-node { fill: rgba(226,232,240,.62); }
html[data-theme="dark"] .mini-node.user { fill: rgba(226,232,240,.9); }
html[data-theme="dark"] .composer { background: rgba(18,23,30,.94); box-shadow: 0 20px 50px rgba(0,0,0,.34); }
html[data-theme="dark"] .loading-node,
html[data-theme="dark"] .inline-error { background: rgba(18,23,30,.97); box-shadow: 0 18px 38px rgba(0,0,0,.38); }
html[data-theme="dark"] .panel-toggle { background: rgba(18,23,30,.72); }
html[data-theme="dark"] .panel-toggle[aria-expanded="true"] { background: rgba(109,151,255,.14); }
html[data-theme="dark"] .panel-backdrop { background: rgba(0,0,0,.48); }

@keyframes node-arrive {
  from { filter: blur(2px); }
  to { filter: blur(0); }
}
@keyframes edge-reveal {
  from { opacity: 0; stroke-dasharray: 2 8; }
  to { opacity: .9; stroke-dasharray: 1 0; }
}
@keyframes inspector-refresh {
  from { opacity: .58; transform: translateY(5px); }
  to { opacity: 1; transform: translateY(0); }
}
@keyframes deck-anchor {
  0% { filter: brightness(1); }
  45% { filter: brightness(.97); }
  100% { filter: brightness(1); }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: .01ms !important; transition-duration: .01ms !important; }
  .graph-node, .node-card { transition-delay: 0s !important; }
}