image map question

#imagemap ul {
	list-style-type: none;
	margin: 0px;
	padding: 0px;
 
 
	height: 163px;
	width: 1023px;
	position: relative;
}
#imagemap li {
	border: medium solid hidden;
 
}
li#b {
	position: absolute;
	left: 92px;
	top: 47px;
	width: 174px;
	height: 84px;
}
li#g {
	position: absolute;
	left: 395px;
	top: 55px;
	width: 135px;
	height: 56px;
}
li#c {
	position: absolute;
	left: 735px;
	top: 53px;
	width: 142px;
	height: 60px;
}
li#b a {
	display: block;
	height: 84px;
	width: 174px;
}
li a em {
	display: none;
}
 My html looks like this 
 
<div id="imagemap">
  <ul>
    <li id="b"><a href="http://www.bbc.co.uk/"><em>bbc site</em></a></li>
    <li id="g"><a href="www.guardian.co.uk"><em>guardian site</em></a></li>
    <li id="c"><a href="www.cnn.com"><em>cnn site</em></a></li>
  </ul>
</div>