.container {
    display: flex;
    flex-wrap: wrap;
/*    justify-content: space-between;*/
}

.box {
    width: 600px;
/*    border: 1px solid black;*/
    box-sizing: border-box; /* this ensures the border is included in the box's total width */
    margin: 10px 10px; /* vertical spacing */
}

/* When the viewport width is less than the combined width of the two boxes plus some padding */
@media (max-width: 1220px) {
    .container {
        flex-direction: column;
        align-items: start;
    }
}