.game-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: 20px;
    touch-action: manipulation;
}

#stats-board {
    font-size: 1.5rem;
    font-weight: bold;
    margin-bottom: 20px;
    color: #38B48B;
    font-family: monospace;
}

.board {
    display: grid;
    grid-template-columns: repeat(4, 75px);
    grid-template-rows: repeat(4, 75px);
    gap: 5px;
    background-color: #bbada0;
    /* Same tone as 2048 */
    padding: 10px;
    border-radius: 8px;
    box-shadow: inset 0 0 10px rgba(0, 0, 0, 0.2), 0 5px 15px rgba(0, 0, 0, 0.3);
}

.tile {
    background-color: #eee4da;
    border-radius: 5px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 2rem;
    font-weight: bold;
    color: #776e65;
    cursor: pointer;
    user-select: none;
    transition: transform 0.15s ease-in-out, background-color 0.2s;
    box-shadow: 0 4px 6px rgba(0, 0, 0, 0.1);
}

.tile:active {
    transform: scale(0.95);
}

.tile.correct {
    background-color: #f2b179;
    color: #f9f6f2;
}

.tile.empty {
    background-color: rgba(238, 228, 218, 0.35);
    /* Translucent empty spot */
    box-shadow: inset 0 0 10px rgba(0, 0, 0, 0.1);
    cursor: default;
}

.tile.empty:active {
    transform: none;
}

/* スマホ向け調整 */
@media (max-width: 400px) {
    .board {
        grid-template-columns: repeat(4, 65px);
        grid-template-rows: repeat(4, 65px);
        gap: 5px;
        padding: 5px;
    }

    .tile {
        font-size: 1.8rem;
    }
}

.controls-hint {
    margin-top: 20px;
    font-size: 0.9rem;
    color: #666;
    text-align: center;
    line-height: 1.5;
}

.back-link {
    display: inline-block;
    color: #666;
    margin-top: 20px;
}

button {
    margin-top: 20px;
    padding: 10px 20px;
    font-size: 1.2rem;
    background-color: #38B48B;
    color: white;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    transition: background-color 0.2s;
    box-shadow: 0 4px 0 #2a8f6d;
}

button:hover {
    background-color: #2a8f6d;
    transform: translateY(2px);
    box-shadow: 0 2px 0 #1b664d;
}

button:active {
    transform: translateY(4px);
    box-shadow: none;
}