Shrink wrap image and horizontally align
HTML
<div id="box">
<a href="#" class="kittyimg"></a>
</div>CSS
#box {
background:#CCC;
width:300px;
height: 100px;
}
a.kittyimg {
background:#CCC url(http://placekitten.com/g/100/100) no-repeat;
width: 100px;
height: 100px;
display: block;
border: 0;
margin: 0 auto;
}