Adding onmouseover to display titles on php outputed game tumbnails

Question

Here i tried to style the default title tooltip with this code, but cant seem to make the images respond to the mouseover for a styled tooltip that should show as a game title?

[data-title]:hover:after {
  opacity: 1;
  transition: all 0.1s ease 0.5s;
  visibility: visible;
}
[data-title]:after {
  content: attr(data-title);
  background-color: #00FF00;
  color: #111;
  font-size: 150%;
  position: absolute;
  padding: 1px 5px 2px 5px;
  bottom: -1.6em;
  left: 100%;
  white-space: nowrap;
  box-shadow: 1px 1px 3px #222222;
  opacity: 0;
  border: 1px solid #111111;
  z-index: 99999;
  visibility: hidden;
}
[data-title] {
  position: relative;
}

the php:

echo '<div class="ran_box">';
echo '<a href="' . $siteurl . 'index.php?act=game&id=' . $games['id'] . '">';
echo '<img src="' . $thumbnail . '" width="60" height="60" data-title="'. $games['title'] . '"></a></div>';