<html>
<head>
<style type="text/css">
a:link, a:visited {
border-style: solid;
border-width: 5px;
border-color: transparent;
}
a:hover {border-color: gray;}
</style>
</head>
<body>
<a href="#">AAA</a>
<a href="#">BBB</a>
<a href="#">CCC</a>
</body>
</html>