<!DOCTYPE html> <html class="reftest-wait"> <!-- Test: fieldset undergoes constraint validation. It should be affected by :invalid pseudo-class. --> <style> fieldset:invalid { display: none; } </style> <body onload="document.getElementById('f').setCustomValidity('foo'); document.documentElement.className='';"> <fieldset> <input id='f'> </fieldset> </body> </html>