JSFiddle - React, Tailwind, and code Playground

HTML

<header>
    <div id="logo">
        Logo
    </div>
    <nav>
        Navigasjon
    </nav>
</header>
<section>
    <div id="slideshow">
        Slideshow
    </div>
    <div id="nyheter">
        <div class="kolonne">Kolonne 1</div>
        <div class="kolonne">Kolonne 2</div>
        <div class="kolonne">Kolonne 3</div>
    </div>
    <div class="tekst">
        Mer innhold her
    </div>
    <div class="tekst">
        Mer innhold her
    </div>
</section>
<footer>
    Footer
</footer>

CSS

header,
body > section,
footer {
    clear: both;
    display: block;
    margin: auto;
    width: 750px;
}
#logo {
    float: left;
    width: 200px;
    height: 200px;
}
nav {
    float: left;
    display: block;
    width: 550px;
    height: 200px;
}
#slideshow {
    width: 100%;
    height: 200px;
}
#nyheter {
    display: table;
    width: 100%;
}
#nyheter .kolonne {
    display: table-cell;
    width: 250px;
    height: 200px;
}
.tekst {
    width: 100%;
    height: 200px;
}

/* Fargesetting for debugging */

#logo { background: blue; }
nav { background: steelblue;  }
#slideshow { background: yellow; }
#nyheter .kolonne:nth-child(1) { background: green; }
#nyheter .kolonne:nth-child(2) { background: limegreen; }
#nyheter .kolonne:nth-child(3) { background: lime; }
.tekst:nth-child(odd)  { background: lightgrey; }
.tekst:nth-child(even) { background: darkgrey; }
footer { background: crimson; }