:root{--bg:#0c1028;--glow:#27306b;--accent:#67e8f9}.board{width:min(82vh,92vw,520px);aspect-ratio:1;display:grid;grid-template-columns:repeat(4,1fr);gap:clamp(5px,1.2vw,10px);padding:clamp(7px,1.5vw,12px);border:1px solid rgba(255,255,255,.14);border-radius:22px;background:rgba(5,8,28,.62);box-shadow:0 24px 70px rgba(0,0,0,.35)}.tile{display:grid;place-items:center;border:0;border-radius:15px;background:rgba(255,255,255,.055);color:#fff;font-size:clamp(20px,6vw,48px);font-weight:1000;box-shadow:inset 0 0 0 1px rgba(255,255,255,.05);transition:transform .12s ease,background .15s ease}.tile.spawn{animation:pop .18s ease}.tile[data-value="2"]{background:#26335f}.tile[data-value="4"]{background:#334a78}.tile[data-value="8"]{background:#176b82}.tile[data-value="16"]{background:#087d7d}.tile[data-value="32"]{background:#3d8f74}.tile[data-value="64"]{background:#8f8b3d}.tile[data-value="128"]{background:#b47a32}.tile[data-value="256"]{background:#c25b3c}.tile[data-value="512"]{background:#c43f61}.tile[data-value="1024"]{background:#9b3fc4;font-size:clamp(16px,5vw,39px)}.tile[data-value="2048"]{background:linear-gradient(135deg,#fde68a,#f472b6);color:#171329;font-size:clamp(16px,5vw,39px);box-shadow:0 0 25px rgba(244,114,182,.45)}.tile.high{background:#312e81;font-size:clamp(13px,4vw,30px)}@keyframes pop{from{transform:scale(.55);opacity:.3}to{transform:scale(1);opacity:1}}@media(max-width:520px){#undo-button{font-size:0}#undo-button::after{content:"↶";font-size:15px}}