Because Dennis asked me to...

<div class="content-top-left-wrapper">
<?php print render($page['content_top']); ?>
</div>
<div class="content-top-right-wrapper">
<?php print render($page['content_top_right']); ?>
</div>
.content-top-right-wrapper,
.content-top-left-wrapper {
width: 50%;
}
.content-top-left-wrapper {
float: right;
}