@media (max-width: 768px) {
        .input-group {
            flex-direction: column;
            align-items: stretch;
        }
        .input-group .form-control,
        .input-group .btn {
            width: 100%;
            margin-bottom: 5px;
        }
        .input-group .btn {
            align-self: flex-end;
        }
    }