.flex-container {
    display: flex;
    flex-wrap: wrap;

    .full-width {
        flex-basis: 100%;
    }
}

.flex-container ul {
    display: flex;
    flex-wrap: wrap;
    margin: 0;
    padding: 0;
    list-style: none;
}

.flex-container ul li {
    flex: 1 1 50%;
    padding: 0;
    box-sizing: border-box;
}

.flex-container ul li.full-width {
    flex-basis: 100%;
}

.flex-container ul li a {
    text-decoration: none;
    outline: none;
    display: block;
    width: 100%;
}