<!doctype HTML>
<html>
<meta charset="utf8">
<title>Display Locking: iframe locking (reference)</title>
<link rel="author" title="Vladimir Levin" href="mailto:vmpstr@chromium.org">
<link rel="help" href="https://drafts.csswg.org/css-contain/#content-visibility">

<style>
div {
  background: blue;
  color: white;
}
</style>

<div>Test passes if there is a box with no text below.</div>
<iframe id="frame" width=400 height=200 srcdoc=''></iframe>
<div>Test passes if there is a box with no text above.</div>
