* {
    box-sizing: border-box;
    border: 1px solid #0065A0;
}
body {
    width: 98%;
    margin: auto;
    background-color: lavender;
}
section, article, aside, footer, header {
    padding: 0.5rem;
}
img, video, embed {
    max-width: 98%;
}

/* default navigation values */
nav {
    display: flex;
    flex-direction: column;
}
nav a {
    flex: 100%;
    margin: 0 5px;
    padding: .5rem;
}

/* medium screen */
@media screen and (min-width: 768px) {
    body {
        display: flex;
        flex-direction: column;
        max-width: 75rem;
    }
    main {
        display: flex;
        flex-wrap: wrap;
    }
    nav, header {
        order: -1;
    }
    nav {
        flex-direction: row;
    }
    nav a {
        flex: auto;
    }
    article {
        flex: 50%;
    }
    aside, section {
        flex: 100%;
    }
    section p {
        column-count: 2;
        column-gap: 20px;
        column-rule: 1px solid #0065A0;
    }
}

/* large screen */
@media screen and (min-width: 1200px) {
    article {
        flex: 35%;
    }
    aside {
        flex: 30%;
    }
}