Untitled

<style type="text/css">
.cnmu125ads {
  display: block;
  list-style: outside none none;
  margin: 5px auto !important;
  padding: 0;
  width: 286px;
}
.cnmu125ads li {float: right;}
.cnmu125ads a {
  background-color: #333;
  border: 4px solid #fff;
  box-shadow: 0 0 0 1px #444;
  color: #fff;
  display: block;
  height: 125px;
  line-height: 125px;
  margin: 5px;
  text-align: center;
  text-decoration: none;
  width: 125px;
}
.cnmu125ads a:hover{background-color: #446faa; color:#fff; border-color:#fc5400;}
</style>
<ul class="cnmu125ads">
<li><a href="#">Ad space</a></li>
<li><a href="#">Ad space</a></li>
<li><a href="#">Ad space</a></li>
<li><a href="#">Ad space</a></li>
</ul>