*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    user-select: none;
}
body{
    background-color: black;
}
body > #board{
    position: absolute;
    width: 80vmin;
    height: 80vmin;
    top: calc(50vh - 40vmin);
    left: calc(50vw - 40vmin);
    background-color: white;
    display: grid;
    grid-template-rows: repeat(10, 1fr);
    grid-template-columns: repeat(10, 1fr);
}
body > #board > .part{
    background-color: white;
    border: 1px black solid;
    font-weight: bolder;
    font-size: 5vmin;
    text-align: center;
    line-height: calc(7.4vmin - 2px);
}
body > #board.act > .part{
    border: none;
    font-size: 0;
}