body {
    margin: 0;
    padding: 0;
    height: 100vh;
    width: 100vw;
    display: flex;
    justify-content: center;
    align-items: center;
    background: #f5f5f5;
}

#schulte-table {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    grid-template-rows: repeat(5, 1fr);
    width: var(--cell-size);
    height: var(--cell-size);
}

.cell {
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: clamp(1rem, 15vmin, 20rem);
    /* auto scale font */
    font-weight: normal;
    user-select: none;
    border: 1px solid #333;
    padding: 5%;
    /* small inner margin */
    box-sizing: border-box;
    text-align: center;
    line-height: 1;
}

.cell.white {
    background-color: white;
}

.cell.gray {
    background-color: #e0e0e0;
}

.center-dot::after {
    content: '';
    width: 20%;
    height: 20%;
    background-color: black;
    border-radius: 50%;
    display: block;
}