:root{--bg: #0d1117;--panel: #161d26;--ink: #e8eef5;--muted: #8fa3b8;--board-edge: rgba(56, 189, 248, .16);--cellbg: #1e2733;--accent: #38bdf8;--good: #4ade80;--bad: #f87171;--hintc: #fbbf24;--cell: 56px}*{box-sizing:border-box}html,body{margin:0;min-height:100%;background:radial-gradient(1100px 640px at 50% -8%,#16273a 0%,var(--bg) 60%);color:var(--ink);font:15px/1.5 ui-sans-serif,system-ui,-apple-system,Segoe UI,Roboto,sans-serif}main{max-width:700px;margin:0 auto;padding:32px 20px 48px;text-align:center}h1{margin:0;font-size:34px;letter-spacing:.5px}h1 span{color:var(--accent);text-shadow:0 0 18px rgba(56,189,248,.45)}.sub{margin:6px auto 20px;max-width:580px;color:var(--muted)}.sub strong,.note strong{color:var(--ink)}#wrap{display:flex;justify-content:center}#board{display:grid;padding:14px;background:var(--panel);border:1px solid var(--board-edge);border-radius:14px;position:relative}.badge{position:absolute;top:-9px;right:14px;font-size:11px;letter-spacing:.6px;text-transform:uppercase;color:var(--muted);background:var(--bg);padding:0 8px;border-radius:6px}.cell{width:var(--cell);height:var(--cell);border:1px solid rgba(143,163,184,.18);border-radius:0;background:var(--cellbg);color:var(--accent);font-size:24px;font-weight:600;line-height:1;cursor:pointer;padding:0;transition:background .12s,box-shadow .12s;position:relative;z-index:0}.cell.rt{border-top:3px solid rgba(203,219,235,.9)}.cell.rb{border-bottom:3px solid rgba(203,219,235,.9)}.cell.rl{border-left:3px solid rgba(203,219,235,.9)}.cell.rr{border-right:3px solid rgba(203,219,235,.9)}.cell:hover{box-shadow:inset 0 0 0 2px #38bdf859}.cell.given{color:var(--ink);background:#232f3f;cursor:default}.cell.selected{box-shadow:inset 0 0 0 2px var(--accent);z-index:1}.cell.conflict{color:var(--bad);box-shadow:inset 0 0 0 2px #f87171a6}.cell.hinted{box-shadow:inset 0 0 0 3px var(--hintc);z-index:1}#board.won .cell:not(.given){color:var(--good)}#board.won .cell{cursor:default}.pad{display:flex;gap:8px;justify-content:center;margin-top:14px}.pad button{width:44px;height:44px;font-size:18px;font-weight:600;border-radius:10px}.hud{min-height:26px;margin:14px 0 4px}#status{color:var(--muted)}#status.good{color:var(--good)}#status.bad{color:var(--bad)}#status.hint{color:var(--hintc)}.controls{display:flex;flex-wrap:wrap;gap:10px;justify-content:center;align-items:center;margin-top:10px}.controls label{color:var(--muted);font-size:14px;display:flex;gap:6px;align-items:center}select,button{background:var(--panel);color:var(--ink);border:1px solid rgba(143,163,184,.35);border-radius:9px;padding:8px 16px;font-size:14px;cursor:pointer;transition:border-color .12s,box-shadow .12s}select:hover,button:hover{border-color:var(--accent);box-shadow:0 0 10px #38bdf840}.note{margin:34px auto 0;max-width:620px;text-align:left;color:var(--muted);font-size:14px;border-top:1px solid rgba(143,163,184,.18);padding-top:18px}@media (max-width: 560px){:root{--cell: 42px}.pad button{width:38px;height:38px}}