​x
 
<html>
<head>
<style type="text/css">
p
{
border: thin solid #FF0000
}
</style>
<script type="text/javascript">
function changeBorderWidth()
{
document.getElementById("p1").style.borderWidth="thick thin";
}
</script>
</head>
<body>
​
<input type="button" onclick="changeBorderWidth()" value="Change border widths" />
​
<p id="p1">This is a paragraph</p>
​
</body>
</html>
​