footer {
    background: lightgreen;
    padding: 8px;
}

footer .flex-container {
    display: flex;
    flex-direction: row;
}

footer .flex-container input {
    margin: auto;
    width: 100px;
    line-height: 50px;
    min-width: 30%;
    font-size: 30px;
}

/* Responsive layout - makes a one column layout instead of a two-column layout */
@media (max-width: 330px) {
    footer .flex-container {
        flex-direction: column;
        bottom: 0;
    }

    footer .flex-container input {
        width: 100%;
        margin: auto auto 4px;
    }

    footer .flex-container input:last-child {
        margin: auto;
    }
}


footer .btn {
    padding: 4px;
    margin-bottom: 3px;
    background-color: #016f1d;
    color: #fff;
    border: none;
    box-shadow: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
}

footer .btn:hover {
    background-color: grey;
}