:root{--bg: #0f172a;--panel: #1e293b;--panel2: #334155;--text: #f8fafc;--muted: #94a3b8;--accent: #6366f1;--accent2: #22c55e;color-scheme:dark}*{box-sizing:border-box;-webkit-tap-highlight-color:transparent}html,body,#root{height:100%;margin:0}body{background:var(--bg);color:var(--text);font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif;overscroll-behavior:none}.app{max-width:480px;margin:0 auto;min-height:100%;display:flex;flex-direction:column;padding:env(safe-area-inset-top) 16px env(safe-area-inset-bottom)}.center{flex:1;display:flex;flex-direction:column;justify-content:center;gap:16px;padding:24px 0}h1{font-size:28px;margin:0 0 4px}.muted{color:var(--muted);font-size:14px}button{font:inherit;border:none;border-radius:12px;padding:14px 18px;background:var(--accent);color:#fff;font-weight:600;cursor:pointer}button:disabled{opacity:.5}button.secondary{background:var(--panel2)}button.ghost{background:transparent;color:var(--muted);padding:8px}input{font:inherit;border:none;border-radius:12px;padding:14px;background:var(--panel);color:var(--text);width:100%}.card{background:var(--panel);border-radius:16px;padding:18px}.topbar{display:flex;justify-content:space-between;align-items:center;padding:12px 0}.stat{display:flex;gap:16px}.stat b{font-size:18px}.board{background:var(--panel2);border-radius:12px;padding:8px;display:grid;grid-template-columns:repeat(4,1fr);gap:8px;aspect-ratio:1;touch-action:none;-webkit-user-select:none;user-select:none}.tile{display:flex;align-items:center;justify-content:center;border-radius:8px;background:#475569;font-weight:800;font-size:clamp(16px,6vw,30px);aspect-ratio:1}.tile.v0{background:#3b4759}.tile.v2{background:#64748b}.tile.v4{background:#7c86a0}.tile.v8{background:#f59e0b}.tile.v16{background:#f97316}.tile.v32{background:#ef4444}.tile.v64{background:#dc2626}.tile.v128{background:#eab308;font-size:clamp(14px,5.5vw,26px)}.tile.v256{background:#ca8a04;font-size:clamp(14px,5.5vw,26px)}.tile.v512{background:#16a34a;font-size:clamp(14px,5.5vw,26px)}.tile.v1024{background:#059669;font-size:clamp(12px,5vw,22px)}.tile.v2048{background:#6366f1;font-size:clamp(12px,5vw,22px)}.banner{border-radius:12px;padding:14px;text-align:center;font-weight:700}.banner.win{background:#22c55e33;color:#4ade80}.banner.info{background:#6366f133;color:#a5b4fc}.error{color:#f87171;font-size:14px}