:root{color-scheme:dark;font-family:ui-sans-serif,system-ui,-apple-system,Segoe UI,Roboto,sans-serif;line-height:1.5}*{box-sizing:border-box}html,body,#root{margin:0;min-height:100vh;background:#0a0a0a;color:#fafafa}.shell{min-height:100vh;display:grid;place-items:center;padding:2rem}.puzzle-container{display:flex;flex-direction:column;align-items:center;gap:1.25rem}.title{margin:0;font-size:2rem;font-weight:700;letter-spacing:-.03em;background:linear-gradient(135deg,#f1c40f,#e74c3c,#9b59b6,#3498db);background-clip:text;-webkit-background-clip:text;color:transparent}.subtitle{margin:0;color:#ffffff80;font-size:.9rem}.stats{display:flex;gap:2rem;padding:.75rem 1.5rem;background:#ffffff0a;border:1px solid rgba(255,255,255,.08);border-radius:.75rem}.stat{display:flex;flex-direction:column;align-items:center;gap:.15rem}.stat-label{font-size:.65rem;text-transform:uppercase;letter-spacing:.15em;color:#fff6}.stat-value{font-size:1.1rem;font-weight:600;font-variant-numeric:tabular-nums;color:#fafafa}.board{display:grid;grid-template-columns:repeat(4,1fr);gap:6px;width:min(85vw,360px);aspect-ratio:1;padding:8px;background:#ffffff08;border:1px solid rgba(255,255,255,.1);border-radius:1rem}.tile{display:flex;align-items:center;justify-content:center;font-size:clamp(1.1rem,4.5vw,1.6rem);font-weight:700;color:#fff;background:#2a2a2a;border:2px solid #333;border-radius:.6rem;cursor:pointer;-webkit-user-select:none;user-select:none;transition:transform .1s ease,box-shadow .15s ease,opacity .3s ease;text-shadow:0 1px 2px rgba(0,0,0,.4);outline:none;-webkit-tap-highlight-color:transparent}.tile:hover:not(:disabled){transform:scale(1.05);box-shadow:0 0 12px #ffffff26;z-index:1}.tile:active:not(:disabled){transform:scale(.95)}.tile-empty{background:transparent!important;border-color:#ffffff0f!important;cursor:default;box-shadow:inset 0 2px 8px #0000004d}.tile-won{animation:pop .4s ease forwards;animation-delay:calc(var(--i, 0) * .03s)}.board .tile:nth-child(1){--i: 0}.board .tile:nth-child(2){--i: 1}.board .tile:nth-child(3){--i: 2}.board .tile:nth-child(4){--i: 3}.board .tile:nth-child(5){--i: 4}.board .tile:nth-child(6){--i: 5}.board .tile:nth-child(7){--i: 6}.board .tile:nth-child(8){--i: 7}.board .tile:nth-child(9){--i: 8}.board .tile:nth-child(10){--i: 9}.board .tile:nth-child(11){--i: 10}.board .tile:nth-child(12){--i: 11}.board .tile:nth-child(13){--i: 12}.board .tile:nth-child(14){--i: 13}.board .tile:nth-child(15){--i: 14}.board .tile:nth-child(16){--i: 15}@keyframes pop{0%{transform:scale(1)}50%{transform:scale(1.15);box-shadow:0 0 20px #ffffff4d}to{transform:scale(1)}}.win-message{font-size:1.1rem;font-weight:600;color:#2ecc71;animation:fadeIn .5s ease}@keyframes fadeIn{0%{opacity:0;transform:translateY(8px)}to{opacity:1;transform:translateY(0)}}.shuffle-btn{padding:.65rem 2rem;font-size:.95rem;font-weight:600;color:#fff;background:linear-gradient(135deg,#3498db,#9b59b6);border:none;border-radius:2rem;cursor:pointer;transition:transform .15s ease,box-shadow .15s ease;outline:none;-webkit-tap-highlight-color:transparent}.shuffle-btn:hover{transform:translateY(-2px);box-shadow:0 6px 20px #3498db59}.shuffle-btn:active{transform:translateY(0)}