mozilla-release/layout/reftests/outline/outline-table-caption-ref.html

<!DOCTYPE html>
<style>
table { outline: 1px solid blue; border-collapse: collapse; }
.caption, .cell { width: 100px; height: 100px; padding: 0; text-align: left; vertical-align: top; }
.caption { background-color: yellow; }
.cell { background-color: lime; }
</style>
<table>
  <tr><td class="caption">Caption</td></tr>
  <tr><td class="cell">Cell</td></tr>
</table>