SO41058343

<!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>