<style type="text/css">
a.rob {
display:block;
margin:10px; padding:0;
width:90px; height:30px;
background:transparent url(/content/img/css/button.png) no-repeat 0 0;
text-decoration:none;
text-indent:-9999px;
}
a.rob:hover {
background-position:0 -30px;
text-decoration:none;
}
</style>
<a href="#" class="rob">Button</a>