<!DOCTYPE html>
<html lang="en-US">
<head>
<style>
#iframe1{
display:block;
height:400px;
width:400px;
margin:0 auto;
}
</style>
</head>
<body>
<iframe id="iframe1" src="/test/test-file-target-top">
<p>Your browser does not support iframes.</p>
</iframe>
</body>
</html>