:root{--bg: #0d1117;--panel: #161d26;--ink: #e8eef5;--muted: #8fa3b8;--board-edge: rgba(56, 189, 248, .16);--cellbg: #1e2733;--accent: #38bdf8;--tile: #f3ece0;--tile-edge: #c9bda8;--tile-ink: #1b2430;--good: #4ade80;--bad: #f87171;--hintc: #fbbf24}*{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)}#wrap{display:flex;justify-content:center}#board{background:var(--panel);border-radius:14px;border:1px solid var(--board-edge);box-shadow:0 20px 60px #00000080;padding:10px;transition:filter .35s ease;touch-action:manipulation}#board.won{filter:drop-shadow(0 0 12px rgba(74,222,128,.45))}.cell{fill:var(--cellbg);stroke:#38bdf81f;stroke-width:1}.cell.hinted{stroke:var(--hintc);stroke-width:3}.domino{fill:var(--tile);stroke:var(--tile-edge);stroke-width:1.5}.domino.dup{fill:#f6b8b8;stroke:var(--bad)}.pip{fill:var(--ink);font:600 20px/1 ui-monospace,SFMono-Regular,Menlo,monospace;text-anchor:middle;dominant-baseline:central;pointer-events:none}.pip.covered{fill:var(--tile-ink)}.pip.dup{fill:#7f1d1d}.join{cursor:pointer}.join-dot{fill:#8fa3b859;pointer-events:none;transition:fill .12s ease,opacity .12s ease}.join-hit{fill:transparent}.join:hover .join-dot{fill:var(--accent);opacity:1}.join.muted .join-dot{opacity:0}.frame{fill:none;stroke:var(--accent);stroke-width:2.5;pointer-events:none;opacity:.5}#tray{display:flex;flex-wrap:wrap;gap:5px;justify-content:center;max-width:520px;margin:16px auto 0}.chip{font:600 12px/1 ui-monospace,SFMono-Regular,Menlo,monospace;letter-spacing:1px;padding:5px 7px;border-radius:6px;border:1px solid rgba(56,189,248,.2);color:var(--muted)}.chip.used{background:var(--tile);border-color:var(--tile-edge);color:var(--tile-ink)}.chip.dup{background:#f6b8b8;border-color:var(--bad);color:#7f1d1d}.hud{margin:16px auto 4px;color:var(--muted);font-size:13px;min-height:20px}#status.win{color:var(--good);font-weight:700;text-shadow:0 0 14px rgba(74,222,128,.5)}#status.bad{color:var(--bad)}.controls{display:flex;gap:10px;justify-content:center;align-items:center;flex-wrap:wrap;margin-top:12px}select,.controls button{font:inherit;border-radius:9px;border:1px solid rgba(56,189,248,.25);background:var(--panel);color:var(--ink);padding:7px 13px;cursor:pointer}.controls button:hover{border-color:var(--accent)}#solve{border-color:var(--accent);color:var(--accent)}label{color:var(--muted);font-size:13px}label select{margin-left:6px}.note{margin:26px auto 0;max-width:620px;color:var(--muted);font-size:13px;text-align:left}.note strong,.note em{color:var(--ink)}