:root{--gap: 0;--accent: #4CAF50;--error: #d32f2f;--muted: #999;--bold: #333}*{box-sizing:border-box}html,body{margin:0;font-family:system-ui,-apple-system,Segoe UI,Roboto,Ubuntu,Helvetica Neue,Arial,sans-serif;background:#f7f7f7;color:#222}.app{width:min(96vw,560px);margin:24px auto;padding:16px;background:#fff;border-radius:12px;box-shadow:0 6px 24px #00000014}.topbar{display:flex;align-items:center;justify-content:space-between;gap:8px;flex-wrap:wrap;margin-bottom:12px}.topbar .left,.topbar .right{display:flex;gap:8px;align-items:center}h1{margin:0 0 8px;font-size:20px}.badge{padding:4px 8px;border-radius:999px;background:#f1f1f1;font-size:12px}.btn{padding:8px 12px;border:1px solid #ddd;background:#fff;border-radius:8px;cursor:pointer}.btn.primary{border-color:var(--accent);color:#fff;background:var(--accent)}.btn.ghost{background:transparent;border-color:#ddd}.info{font-size:14px;color:#555}kbd{padding:2px 6px;border:1px solid #ddd;border-bottom-width:2px;border-radius:4px;background:#fff;font-family:ui-monospace,SFMono-Regular,Menlo,monospace}.board{width:100%;max-width:520px;aspect-ratio:1 / 1;margin:0 auto;display:grid;grid-template-columns:repeat(9,1fr);gap:var(--gap);border:2px solid #ccc;padding:4px;font-size:clamp(12px,2.8vw,22px)}.cell{aspect-ratio:1 / 1;width:100%;height:auto;display:flex;align-items:center;justify-content:center;border:1px solid #ddd;background:#fff;position:relative;cursor:pointer}.cell.prefilled{background:#fafafa;color:#111;font-weight:600}.cell.selected{outline:2px solid #90CAF9;z-index:2}.cell.sameValue{background:#e8f5e9}.cell.error{background:#ffebee}.notes{display:grid;grid-template-columns:repeat(3,1fr);gap:2px;padding:4px;line-height:1;font-size:.48em;color:#666}.cell.block-right{border-right:2px solid #000}.cell.block-bottom{border-bottom:2px solid #000}.footer{margin-top:12px;display:flex;gap:8px;flex-wrap:wrap;align-items:center;justify-content:space-between}.numpad{display:grid;grid-template-columns:repeat(5,1fr);gap:6px}@media (max-width: 480px){.app{padding:12px;margin:16px auto}.btn{padding:6px 10px;font-size:.9rem}.numpad{gap:4px}.info{font-size:13px}}