:root{--bg:#f4f5f7;--surface:#fff;--text:#1f2937;--muted:#6b7280;--line:#cbd5e1;--line-strong:#1f2937;--given:#111827;--entry:#2563eb;--peer:#eef2f7;--same:#cfe0fb;--selected:#a9c7f7;--error-bg:#fde2e2;--error:#c62828;--accent:#2563eb;--accent-text:#fff}@media (prefers-color-scheme:dark){:root{--bg:#111318;--surface:#1a1d24;--text:#e5e7eb;--muted:#9ca3af;--line:#3a3f4b;--line-strong:#9ca3af;--given:#f3f4f6;--entry:#7aa7ff;--peer:#232733;--same:#2c3f66;--selected:#3b5b9a;--error-bg:#4a2226;--error:#ff8a8a;--accent:#3b6fe0}}*{box-sizing:border-box}body{background:var(--bg);color:var(--text);margin:0;font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif}.app{flex-direction:column;gap:14px;max-width:520px;margin:0 auto;padding:16px;display:flex}.topbar{flex-direction:column;gap:6px;display:flex}.topbar h1{margin:0;font-size:1.6rem}.stats{color:var(--muted);justify-content:space-between;font-size:.95rem;display:flex}.stats strong{color:var(--text);font-variant-numeric:tabular-nums}.board-wrap{position:relative}.grid{aspect-ratio:1;background:var(--surface);border:2px solid var(--line-strong);-webkit-user-select:none;user-select:none;grid-template-columns:repeat(9,1fr);display:grid}.cell{border:1px solid var(--line);cursor:pointer;color:var(--entry);justify-content:center;align-items:center;font-size:clamp(1.1rem,5.5vw,1.9rem);display:flex;position:relative}.cell.given{color:var(--given);font-weight:700}.cell.peer{background:var(--peer)}.cell.same{background:var(--same)}.cell.selected{background:var(--selected)}.cell.error{background:var(--error-bg);color:var(--error)}.cell.box-right{border-right:2px solid var(--line-strong)}.cell.box-bottom{border-bottom:2px solid var(--line-strong)}.notes{color:var(--muted);grid-template-rows:repeat(3,1fr);grid-template-columns:repeat(3,1fr);font-size:clamp(.5rem,2.2vw,.8rem);line-height:1;display:grid;position:absolute;inset:2px}.notes span{justify-content:center;align-items:center;display:flex}.controls{flex-direction:column;gap:10px;display:flex}.actions{grid-template-columns:repeat(4,1fr);gap:8px;display:grid}.pad{grid-template-columns:repeat(9,1fr);gap:6px;display:grid}button,select{font:inherit;color:var(--text);background:var(--surface);border:1px solid var(--line);cursor:pointer;border-radius:8px;padding:10px 6px}button:hover:not(:disabled){border-color:var(--accent)}button:disabled{opacity:.35;cursor:default}button[aria-pressed=true],button.primary{background:var(--accent);color:var(--accent-text);border-color:var(--accent)}.pad button{color:var(--entry);flex-direction:column;align-items:center;padding:8px 0 4px;font-size:clamp(1.1rem,5vw,1.6rem);display:flex}.pad button small{color:var(--muted);font-size:.65rem}.new-game{align-items:center;gap:8px;display:flex}.new-game select{flex:1}.best{color:var(--muted);text-align:center;min-height:1.2em;margin:0;font-size:.9rem}.overlay{background:#0000008c;justify-content:center;align-items:center;display:flex;position:absolute;inset:0}.overlay.hidden{display:none}.overlay-card{background:var(--surface);text-align:center;border-radius:12px;flex-direction:column;gap:10px;padding:24px 32px;display:flex}.overlay-card h2{margin:0}.overlay-card p{color:var(--muted);margin:0}