:root{--bg-0: #070b18;--bg-1: #0d1326;--glass: rgba(22, 30, 55, .55);--glass-border: rgba(125, 160, 255, .18);--text: #eaf0ff;--text-dim: #8a96bf;--cyan: #34e1ff;--magenta: #ff4ed5;--gap: clamp(8px, 2.4vw, 14px);--radius: 14px;--slide: .12s;--board: min(92vw, 460px);--size: 4;--cell: calc((var(--board) - var(--gap) * (var(--size) + 1)) / var(--size))}*{box-sizing:border-box}html,body{margin:0;min-height:100%;background-color:var(--bg-0)}body{font-family:Space Grotesk,system-ui,-apple-system,sans-serif;color:var(--text);background:radial-gradient(120% 80% at 15% 0%,rgba(52,225,255,.18),transparent 60%),radial-gradient(120% 80% at 100% 100%,rgba(255,78,213,.16),transparent 55%),linear-gradient(160deg,var(--bg-1),var(--bg-0));background-color:var(--bg-0);min-height:100dvh;display:grid;place-items:center;padding:clamp(12px,4vw,28px);-webkit-tap-highlight-color:transparent;overscroll-behavior:none}.app{width:var(--board);display:flex;flex-direction:column;gap:18px}.topbar{display:flex;justify-content:space-between;align-items:flex-start;gap:14px}.logo{margin:0;font-size:clamp(40px,12vw,60px);font-weight:700;letter-spacing:-.02em;line-height:1;background:linear-gradient(120deg,var(--cyan),#9b8cff 55%,#ff4ed5);-webkit-background-clip:text;background-clip:text;color:transparent;filter:drop-shadow(0 0 18px rgba(52,225,255,.35))}.tagline{margin:6px 0 0;color:var(--text-dim);font-size:13px}.scores{display:flex;gap:10px}.score-box{position:relative;min-width:72px;padding:8px 14px;border-radius:12px;background:var(--glass);border:1px solid var(--glass-border);backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);text-align:center}.score-label{display:block;font-size:10px;text-transform:uppercase;letter-spacing:.12em;color:var(--text-dim)}.score-value{display:block;font-size:22px;font-weight:600;font-variant-numeric:tabular-nums}.score-pop{position:absolute;top:4px;left:0;right:0;text-align:center;font-weight:600;color:var(--cyan);text-shadow:0 0 12px rgba(52,225,255,.7);pointer-events:none;animation:score-pop .7s ease-out forwards}@keyframes score-pop{0%{opacity:0;transform:translateY(0)}20%{opacity:1}to{opacity:0;transform:translateY(-26px)}}.controls{display:flex;align-items:center;justify-content:space-between;gap:12px}.hint{color:var(--text-dim);font-size:12px}.btn{font:inherit;font-weight:600;color:var(--text);padding:10px 18px;border-radius:12px;border:1px solid var(--glass-border);background:var(--glass);backdrop-filter:blur(10px);-webkit-backdrop-filter:blur(10px);cursor:pointer;transition:transform .12s ease,box-shadow .2s ease,border-color .2s ease}.btn:hover{border-color:#34e1ff80;box-shadow:0 0 18px #34e1ff40}.btn:active{transform:scale(.96)}.btn-primary{background:linear-gradient(120deg,var(--cyan),#6f8cff);color:#04101a;border:none;box-shadow:0 0 24px #34e1ff73}.btn-ghost{background:transparent}.board{position:relative;width:var(--board);height:var(--board);padding:var(--gap);border-radius:var(--radius);background:var(--glass);border:1px solid var(--glass-border);backdrop-filter:blur(16px);-webkit-backdrop-filter:blur(16px);box-shadow:0 20px 60px #00000080,inset 0 1px #ffffff0f;touch-action:none}.grid{position:absolute;inset:var(--gap);display:grid;grid-template-columns:repeat(var(--size),1fr);grid-template-rows:repeat(var(--size),1fr);gap:var(--gap)}.cell{border-radius:10px;background:#ffffff09;border:1px solid rgba(255,255,255,.04)}.tiles{position:absolute;inset:var(--gap)}.tile{position:absolute;top:0;left:0;width:var(--cell);height:var(--cell);transition:transform var(--slide) ease-in-out;will-change:transform}.tile-inner{width:100%;height:100%;display:grid;place-items:center;border-radius:10px;font-weight:700;font-size:clamp(20px,7vw,34px);font-variant-numeric:tabular-nums;color:#03101c;background:linear-gradient(135deg,#cfe6ff,#9fc4ff);box-shadow:0 6px 18px #00000059,inset 0 1px #ffffff73}.tile-2 .tile-inner{background:linear-gradient(135deg,#e8f4ff,#b9d6ff)}.tile-4 .tile-inner{background:linear-gradient(135deg,#c8f0ff,#8fd4ff)}.tile-8 .tile-inner{background:linear-gradient(135deg,#6fe3ff,#34b6ff);color:#021326;box-shadow:0 6px 22px #34b6ff80,inset 0 1px #ffffff80}.tile-16 .tile-inner{background:linear-gradient(135deg,#5cf0e2,#19c7b8);color:#021816;box-shadow:0 6px 22px #19c7b880}.tile-32 .tile-inner{background:linear-gradient(135deg,#8affb0,#2fe07a);color:#04190e;box-shadow:0 6px 24px #2fe07a8c}.tile-64 .tile-inner{background:linear-gradient(135deg,#ffd76a,#ffab2e);color:#1c1303;box-shadow:0 6px 24px #ffab2e8c}.tile-128 .tile-inner{background:linear-gradient(135deg,#ff9d6c,#ff6a3d);color:#fff;box-shadow:0 6px 26px #ff6a3d99}.tile-256 .tile-inner{background:linear-gradient(135deg,#ff6fae,#ff3d8b);color:#fff;box-shadow:0 6px 28px #ff3d8b99}.tile-512 .tile-inner{background:linear-gradient(135deg,#ff5edb,#c23bff);color:#fff;box-shadow:0 6px 30px #c23bffa6}.tile-1024 .tile-inner{background:linear-gradient(135deg,#9b8cff,#6a4bff);color:#fff;font-size:clamp(17px,6vw,28px);box-shadow:0 6px 32px #6a4bffb3}.tile-2048 .tile-inner{background:linear-gradient(135deg,#34e1ff,#6a4bff 50%,#ff4ed5);color:#fff;font-size:clamp(17px,6vw,28px);box-shadow:0 0 40px #7a78ffd9;animation:trophy-glow 1.6s ease-in-out infinite}.tile-super .tile-inner{background:linear-gradient(135deg,#1a1030,#3a1a5e);color:#fff;font-size:clamp(15px,5vw,24px);box-shadow:0 0 40px #7a78ffcc}@keyframes trophy-glow{0%,to{box-shadow:0 0 32px #7a78ffb3}50%{box-shadow:0 0 52px #ff4ed5e6}}.tile-new .tile-inner{animation:tile-appear .18s ease-out}@keyframes tile-appear{0%{transform:scale(0);opacity:0}to{transform:scale(1);opacity:1}}.tile-merged{z-index:2}.tile-merged .tile-inner{animation:tile-merge .2s ease var(--slide) backwards}@keyframes tile-merge{0%{transform:scale(0)}50%{transform:scale(1.2)}to{transform:scale(1)}}.overlay{position:absolute;top:0;right:0;bottom:0;left:0;border-radius:var(--radius);display:flex;flex-direction:column;align-items:center;justify-content:center;gap:18px;background:#070b18b8;backdrop-filter:blur(8px);-webkit-backdrop-filter:blur(8px);opacity:0;pointer-events:none;transition:opacity .25s ease}.overlay.is-visible{opacity:1;pointer-events:auto}.overlay-title{margin:0;font-size:clamp(24px,7vw,34px);font-weight:700;text-align:center;padding:0 16px}.overlay-actions{display:flex;gap:12px}.overlay:not(.is-win) #keep-playing{display:none}@media(prefers-reduced-motion:reduce){.tile,.tile-inner,.score-pop{animation:none!important;transition:none!important}}