<div class="outer-div"><div class="inner-div"></div></div>
body
{
  background-color: #fcfcfc;
}
.outer-div
{
  position: absolute;
  bottom: 30px;
  width: 100%;
}
.inner-div
{
  margin: 0 auto;
  width: 100px;
  height: 100px;
  background-color: #ccc;
  border-radius: 3px;
}

External CSS

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External JavaScript

This Pen doesn't use any external JavaScript resources.