password_manager/form_with_iframe.html (17 lines of code) (raw):
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Login Form with Iframe Loading a Cross-Origin Login Form</title>
</head>
<body>
<form action="success.html" method="POST">
<h2>Login form:</h2>
<input name="u" placeholder=username />
<input name="p" type=password placeholder=current-password autocomplete=current-password />
<input type=submit value="Log In"/>
</form>
<!-- The src value can be edited in DevTools via the Console by selecting the <iframe> in the Inspector,
and then entering e.g. `$0.src = "https://example.com"` (without the backticks). Note that many
websites block being loaded in an iframe by using the X-Frame-Options header. -->
<iframe src="https://bugs.mattn.ca/pwmgr/login_and_change_form.html"></iframe>
</body>
</html>