d a gray bottom border around halfway down on the third
  page. The yellow box should be on the top of the gray border.
</div>
<div style="height:0;">
  <div style="height:675px;"></div>
  <div style="height:50px; background:gray;"></div>
</div>
<div style="width:50%; height:1450px; background:yellow;"></div>
