.board-section {
    background: var(--color-board);
    border-radius: var(--radius-lg);
    padding: 15px;
    box-shadow: var(--shadow-soft);
    --cell-size: 100px;
    --cell-gap: 12px;
    touch-action: none;
}

.board {
    position: relative;
    display: inline-block;
}

.grid {
    display: grid;
    grid-template-columns: repeat(4, var(--cell-size));
    grid-template-rows: repeat(4, var(--cell-size));
    gap: var(--cell-gap);
}

.cell {
    background: var(--color-cell-empty);
    border-radius: var(--radius-md);
}

.tiles-layer {
    position: absolute;
    inset: 0;
    pointer-events: none;
}

.tile {
    position: absolute;
    top: 0;
    left: 0;
    transition: transform 120ms ease-in-out;
    will-change: transform;
}

.tile-inner {
    width: 100%;
    height: 100%;
    display: flex;
    justify-content: center;
    align-items: center;
    border-radius: var(--radius-md);
    font-weight: 800;
    color: var(--color-text-dark);
    background: #eee4da;
    font-size: calc(var(--cell-size) * 0.38);
    user-select: none;
}

.tile-inner.pop-in {
    animation: tilePopIn 160ms ease-out;
}

.tile-inner.merge-pop {
    animation: tileMergePop 160ms ease-out;
}

@keyframes tilePopIn {
    0% { transform: scale(0); opacity: 0; }
    60% { transform: scale(1.1); opacity: 1; }
    100% { transform: scale(1); }
}

@keyframes tileMergePop {
    0% { transform: scale(1); }
    50% { transform: scale(1.16); }
    100% { transform: scale(1); }
}

.tile-2 { background: #eee4da; color: var(--color-text-dark); }
.tile-4 { background: #ede0c8; color: var(--color-text-dark); }
.tile-8 { background: #f2b179; color: var(--color-text-light); }
.tile-16 { background: #f59563; color: var(--color-text-light); }
.tile-32 { background: #f67c5f; color: var(--color-text-light); }
.tile-64 { background: #f65e3b; color: var(--color-text-light); }
.tile-128 { background: #edcf72; color: var(--color-text-light); font-size: calc(var(--cell-size) * 0.32); }
.tile-256 { background: #edcc61; color: var(--color-text-light); font-size: calc(var(--cell-size) * 0.32); }
.tile-512 { background: #edc850; color: var(--color-text-light); font-size: calc(var(--cell-size) * 0.32); }
.tile-1024 { background: #edc53f; color: var(--color-text-light); font-size: calc(var(--cell-size) * 0.28); }
.tile-2048 { background: #edc22e; color: var(--color-text-light); font-size: calc(var(--cell-size) * 0.28); }
.tile-4096 { background: #3c3a32; color: var(--color-text-light); font-size: calc(var(--cell-size) * 0.28); }
.tile-8192 { background: #2c2a24; color: var(--color-text-light); font-size: calc(var(--cell-size) * 0.26); }
.tile-16384 { background: #1e1c18; color: var(--color-text-light); font-size: calc(var(--cell-size) * 0.22); }
.tile-32768 { background: #171512; color: var(--color-text-light); font-size: calc(var(--cell-size) * 0.22); }
.tile-65536 {
    background: #000000;
    color: var(--color-text-light);
    font-size: calc(var(--cell-size) * 0.2);
    box-shadow: 0 0 18px rgba(237, 194, 46, 0.65);
}