#board {
    display: grid;
    grid-template-columns: repeat(6, 1fr);
    grid-template-rows: repeat(6, 1fr);
    width: 45vmin;
    height: 45vmin;
    margin-top: 20px;
}

.slot {
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    background-color: #f0f0f0;
    position: relative;
    border: 2px solid #f6f6f6;

}
.slot.highlight {
    border: 3px solid #007bff;
    transform: rotateY(360deg);
    transform-style: preserve-3d;
    transition: transform 1s;
}
.slot-coord {
    position: absolute;
    top: 2px;
    right: 2px;
    font-size: 12px;
    background: #666;
    color: white;
    border-radius: 3px;
    padding: 2px;
}
.slot-indicator {
    font-size: 25px;
}