<!DOCTYPE HTML>
<title>Testcase, bug 764354</title>
<style>
#outer {
  display: -moz-box;
  overflow: hidden;
  -moz-box-orient: vertical;
  width: 300px;
  height: 100px;
  background: yellow; color: black;
}
.inner {
  background: aqua; color: black;
  text-align: center;
}
</style>

<div id="outer">
  <div class="inner">Text</div>
  <div class="inner">Text</div>
</div>