HTML:

```
<body class="pageStyle">
<h1>The Amazing World of CSS</h1>
<p><strong>Sed ut perspiciatis</strong> unde omnis iste natus error sit <em>voluptatem accusantium</em> doloremque laudantium, totam rem aperiam, eaque ipsa quae ab illo <strong>inventore veritatis et quasi architecto beatae</strong> vitae dicta sunt explicabo. Nemo enim ipsam voluptatem quia voluptas sit aspernatur aut odit aut fugit, sed quia  eos qui ratione voluptatem sequi nesciunt. Learn more about CSS at the <a href="http://www.w3.org/Style/CSS/">W3C CSS Home Page</a>.</p>
</body>

```

CSS:

```
.pageStyle {
        font-family: 'Helvetica Neue', Arial, Helvetica, sans-serif;
        font-size: 18px;
    }

```

Result: <https://jsfiddle.net/2tqxadpn/>

Why is the `<h1>` tag not 18px?