:before line on table-cell element

difference between firefox & chrome.

HTML

<div id="wrapper">
    <div class="col1">col1 col1 col1</div>
    <div class="outer"><div class="col2">col2 col2 col2</div></div>
    <div class="col3">col3 col3 col3</div>    
</div>

CSS

#wrapper {
  margin: 40px 0 0 0;
  position: relative;
  background: yellow;
  display: table;
}

#wrapper > div > div {
  width: 33%;
  display: table-cell;
  vertical-align: middle;
  height: 75px;
  width: 60px;
  border: 1px solid #ccc;
  text-align: center;
  position: relative;
}


span {height: 75px; width: 100%; position: absolute; border-top: 5px solid lightblue; display: block; top: -5px;}