main {
    display: flex;
    align-items: flex-start;
    justify-content: center;
}

.botoes {
    flex-flow: column nowrap;
    width: 100%;
}

.botoes button:last-child, .botoes a.button:last-child {
    margin: 0 2px 2px 0;
}

@media (min-width: 768px) {
    .botoes {
        width: 400px;
    }
}