Conteúdo do div.um

Lorem ipsum dolor sit amet, consectetuer adipiscing elit.

HTML

<div class="um">
  <h1>Conteúdo do div.um</h1>
  <p>Lorem ipsum dolor...</p>
</div>

CSS

<style>
html, body { margin:0; height: 100%;}
.um { background: black; color: white; padding:0 20px; height: 100%; }
h1 { margin:0;}
</style>