style.css

@import url('https://fonts.googleapis.com/css?family=Quicksand');

html, body {
    margin: 0;
    font-family: 'Quicksand', sans-serif;
}

body {
   position: absolute;
   top: 0;
   bottom: 0;
   left: 0;
   right: 0;
}

header {
    padding: 0 30px;
    display: flex;
    flex-direction: column;
    align-items: center;
    text-transform: uppercase;
}

header a {
    padding: 30px 0;
    text-decoration: none;
    color: #333;
}

a[href="/"] h1 {
    margin: 0;
}

header nav {
    display: flex;
    flex-wrap: wrap;
    justify-content: center;
}

header nav a {
    margin: auto;
    margin-left: 30px;

}

header nav a:hover {
    color: #555;
    text-decoration: underline;
}

main {
    height: 100%;
    padding: 30px;
    overflow-x: auto; 
}

iframe {
    display: block;
    margin: auto;
    min-width: 1200px;
    width: 100%;
    height: 100%;
}

article {
    margin-bottom: 60px;
}

@media all and (min-width: 786px) {
    header {
        flex-direction: row;
        justify-content: space-between;
    }

    header, main {
        max-width: 1200px;
        margin: auto;
    }
}