h 100%

by Symphony

HTML

<div class="wr">
    
    <p>Lorem ipsum dolor sit amet, consectetur adipisicing elit. Voluptate eius vel quasi reiciendis totam animi eos ad nisi aspernatur quaerat quia praesentium dolorum suscipit alias dicta dolores distinctio accusamus molestiae.</p>
</div>

CSS

html,body {
    height: 100%;
    min-height: 100%;
}
.wr {
    min-height: 100%;
    background: #f55
}