/* Game Area */
.game-area{flex:1;display:flex;align-items:center;justify-content:center;padding:1rem;overflow:hidden}
#board-wrap{width:100%;max-width:400px}
#board{display:grid;grid-template-columns:repeat(4,1fr);gap:12px;perspective:1000px;padding:4px}
.card{aspect-ratio:1;position:relative;transform-style:preserve-3d;transition:transform .38s cubic-bezier(.32,.72,0,1), opacity .38s ease;cursor:pointer;-webkit-tap-highlight-color:transparent}
.card.flipped{transform:rotateY(180deg)}
.card.matched{opacity:0;pointer-events:none}
.card:active:not(.flipped):not(.matched){transform:scale(.95)}

.card-face{position:absolute;inset:0;backface-visibility:hidden;border-radius:14px;display:flex;align-items:center;justify-content:center}
.card-front{background:#fff;transform:rotateY(180deg);font-size:2.5rem;box-shadow:0 4px 16px rgba(0,0,0,.06)}
.card-back{background:#e8e5e0;border:2px solid rgba(0,0,0,.04);transition:background .13s}
.card:hover .card-back{background:#e2ded8}