.layout--two-column7030 {
    display: flex;
    flex-wrap: wrap;
}

.layout--two-column7030>.layout__region {
    flex: 0 1 100%;
}

@media screen and (min-width: 40em) {
    .layout--two-column7030>.layout__region--first {
        flex: 0 1 30%;
    }
    .layout--two-column7030>.layout__region--second {
        flex: 0 1 70%;
    }
}