<!DOCTYPE html>
<link rel="help" href="https://drafts.csswg.org/css-contain/#content-visibility">
<link rel="help" href="https://crbug.com/1316517">
<meta name="assert" content="Ensure content-visibility: hidden doesn't apply to <output> elements">
<style>
output {
 content-visibility: hidden;
}
</style>
<output>
  <iframe></iframe>
