css square image

1/* THE HTML  */
2<div class="thumb1"> </div>
3/* THE CSS */
4.thumb1 { 
5  background: url(blah.jpg) 50% 50% no-repeat; /* 50% 50% centers image in div */
6  width: 250px;
7  height: 250px;
8}
9
10.thumb1:hover { 
11/* HOVER STYLE HERE */
12}