#board {
    display: grid;
    grid-template-columns: repeat(8, 45px);
    grid-template-rows: repeat(8, 45px);
    border: 1px solid black;
    width: 360px; /* 8 * 45 */
}

.cell {
    width: 45px;
    height: 45px;
    background-color: lightgreen;
    border: 1px solid black;
    box-sizing: border-box;
}

.piece {
    width: 40px;
    height: 40px;
    border-radius: 50%;
    margin: 2.5px;
    position: relative;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
}

.black {
    background-color: black;
}

.white {
    background-color: white;
}