*{margin:0;padding:0;box-sizing:border-box}
body{background:#1a1a1a;color:#fff;font-family:sans-serif;padding:15px}
.container{max-width:450px;margin:0 auto}
.header{display:flex;justify-content:space-between;align-items:center;margin-bottom:15px;flex-wrap:wrap;gap:10px}
#restart{padding:8px 12px;background:#5b42f3;border:none;border-radius:6px;color:#fff;cursor:pointer}
.grid{display:grid;grid-template-columns:repeat(4,1fr);gap:8px;background:#333;padding:8px;border-radius:8px;aspect-ratio:1/1}
.cell{background:#444;border-radius:6px;display:flex;align-items:center;justify-content:center;font-weight:bold;font-size:clamp(16px,5vw,26px)}
.over{position:fixed;top:0;left:0;width:100%;height:100%;background:rgba(0,0,0,.8);display:none;flex-direction:column;gap:20px;align-items:center;justify-content:center;font-size:22px}
.over button{padding:10px 18px;background:#5b42f3;border:none;border-radius:6px;color:#fff}
.c2{background:#eee4da;color:#776e65}
.c4{background:#ede0c8;color:#776e65}
.c8{background:#f2b179;color:#fff}
.c16{background:#f59563;color:#fff}
.c32{background:#f67c5f;color:#fff}
.c64{background:#f65e3b;color:#fff}
.c128{background:#edcf72;color:#fff}
.c256{background:#edcc61;color:#fff}
.c512{background:#edc850;color:#fff}
.c1024{background:#edc53f;color:#fff}
.c2048{background:#edc22e;color:#fff}
.grid {
  touch-action: none;
  -webkit-touch-callout: none;
  user-select: none;
}