A Pen by Matt Steele.

index.html

<div class="container">Main Container @ 960px
  <div class="row">
    <div class="column-4">A Column @ 320px</div>
    <div class="column-4">Column @ 320px</div>
    <div class="column-4">Column @ 320px</div>
  </div>
</div>

Kycsz.markdown

Kycsz

A Pen by Matt Steele on CodePen.

License.

style.css

* {
  box-sizing: border-box;
  text-align: center;
  padding-top: 30px;
}
.container {
	margin: 0 auto;
  width: 960px;
  background: #ddd;
}
.row {
  width: auto;
  overflow: auto;
  height: 400px;
}
.column-4 {
  width: 320px;
  height: 300px;
  float: left;
  background: #888;
  padding-right: 30px;
  border: 1px solid #fff;
  margin: 0;
}