* {
    box-sizing: border-box;
}

#container {
    width: 75vmin;
    height: 75vmin;
}

.row-div {
    display: flex;
}

.column-div {
    border: 1px solid black;
}

main {
    margin-top: 40px;
    display: flex;
    justify-content: space-evenly;
    align-items: center;
    flex-wrap: wrap;
    gap: 15px;
}

.btn {
    display: flex;
    flex-flow: column wrap;
    justify-content: center;
    gap: 20px;
}

.btn button {
    font-size: 1rem;
    border-radius: 8px;
    padding: 0.5rem;
}

h1 {
    text-align: center;
    font-size: 2.5rem;
}

@media screen and (max-width: 720px) {
    .btn {
        flex-direction: row;
        gap: 10px;
    }
}