Containers

They contain things.

.container-s (640px)

.container-m (960px)

.container-l (1280px)

.container-full-width (100%)

<div class="container-s">
	<p>640px</p>
</div>
<div class="container-m">
	<p>960px</p>
</div>
<div class="container-l">
	<p>1280px</p>
</div>
<div class="container-full-width">
	<p>100%</p>
</div>