<!DOCTYPE html>
<html>
<head>
<style>
iframe {width:97vw;height: 65vh;}
</style>
</head>
<body>
<fieldset>
<button><a href='http://www.w3schools.com/' target='ifrm1'>W3Schools</a></button>
<button><a href='http://plainjs.com' target='ifrm1'>PlainJS</a></button>
</fieldset>
<iframe name='ifrm1' src='index2.html'></iframe>
</body>
</html>
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<h1>index2.html</h1>
</body>
</html>