:root {
    color-scheme: dark;
    --ui-bg: oklch(0.31 0.009 270); --ui-panel: oklch(0.28 0.009 270);
    --ui-field: oklch(0.23 0.007 270); --ui-border: oklch(0.39 0.012 270);
    --ui-text: oklch(0.92 0.006 270); --ui-muted: oklch(0.75 0.012 270);
    --primary: oklch(0.55 0.21 276); --focus: oklch(0.8 0.12 276);
    --paper: oklch(0.985 0.008 85); --paper-2: oklch(0.95 0.015 85);
    --ink: oklch(0.25 0.012 70); --text-dim: oklch(0.43 0.012 70);
    --accent: oklch(0.48 0.14 40); --accent-2: var(--accent);
    --accent-soft: oklch(0.92 0.04 55); --line: oklch(0.48 0.01 70);
    --line-soft: oklch(0.8 0.01 70); --good: oklch(0.42 0.1 150);
    --good-soft: oklch(0.95 0.025 150); --symbol-scale: .58;
}
* { box-sizing: border-box; }
body { margin: 0; padding: 0 24px 64px; background: var(--ui-bg); color: var(--ui-text); font: 15px/1.5 system-ui, sans-serif; }
body > * { max-width: 1120px; margin-left: auto; margin-right: auto; }
button, input, textarea, select { font: inherit; }
button, a, input, select, summary { touch-action: manipulation; }
button, select, input:not([type=checkbox]), summary { min-height: 44px; }
button { border: 1px solid var(--ui-border); border-radius: 8px; padding: 10px 16px; background: var(--ui-field); color: var(--ui-text); cursor: pointer; font-weight: 600; }
button:hover:not(:disabled) { background: var(--ui-border); }
button:disabled { opacity: .45; cursor: default; }
button.primary { background: var(--primary); border-color: var(--primary); }
button.primary:hover { filter: brightness(1.12); background: var(--primary); }
:focus-visible { outline: 3px solid var(--focus); outline-offset: 3px; }
a { color: inherit; text-decoration: none; display: inline-flex; align-items: center; min-height: 44px; }
a:hover { text-decoration: underline; }
.topbar { display: flex; align-items: center; justify-content: space-between; gap: 16px; border-bottom: 1px solid var(--ui-border); padding: 12px 0; }
.topbar span { font-size: 11px; letter-spacing: .1em; color: var(--ui-muted); }
header { padding: 28px 0 20px; }
h1 { font-size: 32px; line-height: 1.15; letter-spacing: -.025em; margin: 0; }
.subtitle { color: var(--ui-muted); max-width: 70ch; margin: 12px 0 0; }
.how-to { margin-bottom: 16px; border-bottom: 1px solid var(--ui-border); }
.how-to summary { cursor: pointer; padding: 8px 0; font-weight: 600; }
.how-to .body { padding: 0 0 16px; color: var(--ui-muted); max-width: 75ch; }
.example-line { color: var(--ui-text); }
.controls-panel { padding: 20px; background: var(--ui-panel); border: 1px solid var(--ui-border); border-radius: 12px; }
.controls-tabs { display: flex; gap: 8px; border-bottom: 1px solid var(--ui-border); margin-bottom: 20px; padding-bottom: 12px; }
.tab-btn { background: transparent; border-color: transparent; }
.tab-btn[aria-selected=true] { background: var(--ui-border); }
.tab-panel { display: none; }
.tab-panel.active { display: block; }
.controls-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(160px, 1fr)); gap: 16px; }
.control-group { display: flex; flex-direction: column; gap: 6px; min-width: 0; }
.control-group.span-2 { grid-column: span 2; }
.control-group label { font-size: 13px; font-weight: 600; }
.control-group input, .control-group select, .control-group textarea { width: 100%; min-width: 0; border: 1px solid var(--ui-border); border-radius: 8px; padding: 9px 10px; background: var(--ui-field); color: var(--ui-text); }
.hint { color: var(--ui-muted); font-size: 12px; }
.switch-row, .collection-settings { display: flex; align-items: center; flex-wrap: wrap; gap: 12px 24px; margin-top: 16px; }
.collection-settings { padding-top: 16px; border-top: 1px solid var(--ui-border); }
.collection-settings .control-group { flex: 1 1 230px; }
.switch { display: flex; align-items: center; gap: 8px; min-height: 44px; cursor: pointer; font-size: 13px; }
input[type=checkbox] { width: 20px; height: 20px; accent-color: var(--primary); flex-shrink: 0; }
.actions { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin-top: 20px; }
.score-chip { color: var(--ui-muted); font-size: 12px; margin-left: auto; }
#feedback { color: var(--ui-muted); min-height: 24px; margin-top: 8px; margin-bottom: 8px; }
.pager { display: flex; justify-content: space-between; align-items: center; gap: 12px; margin-bottom: 16px; }
#page-status { text-align: center; font-variant-numeric: tabular-nums; }
#printable-area { color-scheme: light; background: var(--paper); color: var(--ink); border-radius: 12px; padding: 28px; }
.sheet-header { display: flex; justify-content: space-between; gap: 24px; padding-bottom: 20px; border-bottom: 1px solid var(--line-soft); }
.sheet-title { font-size: 22px; font-weight: 700; line-height: 1.3; overflow-wrap: anywhere; }
.sheet-title span { display: block; font-size: 11px; text-transform: uppercase; letter-spacing: .1em; margin-bottom: 8px; color: var(--text-dim); }
.sheet-note { max-width: 38ch; font-size: 13px; color: var(--text-dim); overflow-wrap: anywhere; }
.exercise-header { display: flex; justify-content: space-between; gap: 16px; padding: 20px 0 14px; }
.exercise-title { font-weight: 700; font-size: 18px; }
.exercise-meta { color: var(--text-dim); font-size: 13px; white-space: nowrap; }
.exercise-layout { display: grid; grid-template-columns: minmax(0, 1fr) 210px; gap: 28px; }
.exercise-layout.below, .exercise-layout.hidden { grid-template-columns: minmax(0, 1fr); }
.grid-panel { min-width: 0; }
.instruction { color: var(--text-dim); font-size: 13px; margin-bottom: 12px; }
.matrix-wrap { max-width: 100%; overflow: auto; overscroll-behavior-x: contain; padding: 3px; }
.matrix-grid { --actual-cell: var(--cell-size); display: grid; grid-template-columns: repeat(var(--grid-size), var(--actual-cell)); width: max-content; border: 1px solid var(--line); margin: 0 auto; }
.matrix-cell { width: var(--actual-cell); height: var(--actual-cell); display: flex; justify-content: center; align-items: center; border: .5px solid var(--line-soft); font-size: calc(var(--actual-cell) * var(--symbol-scale)); font-family: system-ui, 'Segoe UI Symbol', sans-serif; position: relative; }
.matrix-cell.hidden { background: var(--accent-soft); }
.block-top { border-top: var(--hidden-border); }.block-bottom { border-bottom: var(--hidden-border); }.block-left { border-left: var(--hidden-border); }.block-right { border-right: var(--hidden-border); }
.block-number { font: 700 11px system-ui; color: var(--ink); position: absolute; top: 0; left: 3px; }
.coord { position: absolute; top: 0; left: 1px; font: 8px system-ui; color: var(--text-dim); }
.matrix-hint { font-size: 11px; color: var(--text-dim); margin: 8px 0; }
.puzzle-footer { display: flex; flex-wrap: wrap; gap: 8px 16px; font-size: 12px; margin-top: 16px; }
.rule-chip { overflow-wrap: anywhere; }
.answer-panel { border-top: 1px solid var(--line-soft); padding-top: 12px; }
.answer-kicker, .answer-copy, .solution-note { color: var(--text-dim); font-size: 12px; }
.answer-title { font-size: 20px; font-weight: 700; margin: 4px 0; }
.answer-block { margin: 16px 0; max-width: 210px; break-inside: avoid; }
.answer-block-label { font-size: 12px; margin-bottom: 6px; font-weight: 700; }
.answer-grid { display: grid; border: 1px solid var(--line); }
.answer-cell { display: flex; align-items: center; justify-content: center; border: .5px solid var(--line-soft); background: var(--paper); }
.placeholder .answer-cell { color: var(--line-soft); }
.below .answer-panel { display: flex; align-items: flex-start; flex-wrap: wrap; gap: 16px; }
.below .answer-block { width: 180px; }
#print-pages { display: none; }
body[data-theme=ocean] { --paper: oklch(0.985 0.008 240); --accent: oklch(0.47 0.12 240); --accent-soft: oklch(0.92 0.03 240); }
body[data-theme=forest] { --paper: oklch(0.985 0.008 145); --accent: oklch(0.43 0.1 145); --accent-soft: oklch(0.92 0.03 145); }
body[data-theme=mono] { --paper: oklch(0.99 0.002 270); --accent: oklch(0.3 0.002 270); --accent-soft: oklch(0.92 0.002 270); }
body[data-theme=dark] { --paper: oklch(0.24 0.008 270); --ink: oklch(0.94 0.005 270); --text-dim: oklch(0.77 0.008 270); --line: oklch(0.72 0.01 270); --line-soft: oklch(0.47 0.01 270); --accent: oklch(0.8 0.1 276); --accent-soft: oklch(0.38 0.04 276); }
@media (max-width: 850px) {
    .exercise-layout { grid-template-columns: minmax(0, 1fr); }
    .answer-panel { display: flex; flex-wrap: wrap; align-items: flex-start; gap: 12px 20px; }
    .answer-kicker, .answer-title, .answer-copy, .solution-note { width: 100%; margin: 0; }
    .answer-block { width: 180px; margin: 8px 0; }
    .sheet-header { flex-direction: column; gap: 12px; }
}
@media (max-width: 600px) {
    body { padding: 0 12px 32px; }
    .topbar span { display: none; }
    header { padding: 24px 0 12px; } h1 { font-size: 26px; }
    .controls-panel { padding: 12px; }
    .controls-tabs { gap: 0; justify-content: space-between; }.tab-btn { padding: 8px; font-size: 14px; }
    .controls-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; }
    .control-group input, .control-group select, .control-group textarea { font-size: 16px; }
    .actions button { flex: 1 1 44%; padding: 10px 8px; font-size: 13px; }
    .score-chip { width: 100%; margin: 4px 0 0; }
    #printable-area { padding: 14px; }.sheet-title { font-size: 20px; }
    .exercise-header { flex-direction: column; gap: 4px; }.exercise-title { font-size: 16px; }
    .pager button { font-size: 13px; padding: 8px; } #page-status { font-size: 12px; }
    .matrix-grid { --actual-cell: max(24px, min(var(--cell-size), calc((100vw - 62px) / var(--grid-size)))); }
}
@media (prefers-reduced-motion: reduce) { *, *::before, *::after { scroll-behavior: auto !important; transition: none !important; animation: none !important; } }
@media print {
    @page { size: A4 portrait; margin: 12mm; }
    :root { color-scheme: light; background: oklch(0.99 0.002 270); }
    body { padding: 0; background: oklch(0.99 0.002 270); }
    body > :not(#print-pages) { display: none !important; }
    #print-pages { display: block; color: oklch(0.2 0.005 270); --ink: oklch(0.2 0.005 270); --text-dim: oklch(0.4 0.005 270); --paper: oklch(0.99 0.002 270); --line: oklch(0.4 0.005 270); --line-soft: oklch(0.7 0.005 270); --accent-soft: oklch(0.94 0.003 270); --hidden-border: 2px dashed currentColor; }
    .print-page { background: var(--paper); }
    .print-solutions { break-before: page; }
    .print-page .exercise { break-inside: avoid; margin-bottom: 6mm; }
    .print-page .sheet-header { break-after: avoid; }
    .print-page .exercise-layout { display: block; }
    .print-page .matrix-grid { --actual-cell: min(var(--cell-size), 7.2mm); }
    .print-page .matrix-wrap { overflow: visible; padding: 0; }
    .print-page .matrix-hint, .print-page .answer-copy, .print-page .solution-note, .print-page .answer-title, .print-page .answer-kicker { display: none; }
    .print-page .answer-panel { display: flex; gap: 8mm; flex-wrap: wrap; margin-top: 5mm; }
    .print-page .answer-block { width: 38mm; margin: 0; }
    .print-page .answer-cell { min-height: 7mm !important; font-size: 16px !important; }
    .print-page .sheet-header { display: block; padding: 0 0 3mm; }
    .print-page .sheet-note { max-width: none; }
    .print-page .exercise-header { padding: 4mm 0 2mm; }
    .print-page .puzzle-footer { margin-top: 3mm; }
    .print-page .placeholder .answer-cell { color: transparent; }
    .print-page h2 { margin: 0 0 4mm; }
    .print-page .answer-row { break-inside: avoid; margin-bottom: 6mm; }
    .print-page .answer-row .answer-panel { border: 0; padding: 0; }
}