* {
    margin: 0;
    box-sizing: border-box;
}

#container {
    height: 100vh;
    width: 100vw;
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
}
td {
    border: 1px solid black;
    height: 4rem;
    width: 4rem;
    text-align: center;
    border-radius: 50%;
}
th {
    height: 4rem;
    width: 4rem;
    text-align: center;
}
button {
    background: none;
    border: none;
    outline: none;
    height: 3rem;
    width: 3rem;
    font-size: 2rem;
    font-weight: bold;
    cursor: pointer;
}