:root{color-scheme:dark}*{box-sizing:border-box}body{margin:0;background:#0b0b0b;color:#e5e7eb;font-family:ui-sans-serif,system-ui,-apple-system,Segoe UI,Roboto,sans-serif}h2{margin:0 0 10px}.controls{display:flex;gap:8px;align-items:center;flex-wrap:wrap;margin-bottom:12px}button,select,input{font:inherit}button{padding:6px 10px;border-radius:6px;border:1px solid #333;background:#111;color:#e5e7eb;cursor:pointer}button:hover{background:#161616}.grid{display:grid;grid-template-columns:repeat(20,1fr);gap:2px}.cell{padding:4px 6px;background:#1b1b1b;color:#d9f99d;border-radius:4px;text-align:center;font-size:12px}pre.log{background:#111;color:#0f0;padding:12px;border-radius:6px;max-height:240px;overflow:auto}