<!DOCTYPE html> <html class="reftest-wait"> <!-- Test: if button has a disabled fieldset ancestor, but is in the first legend, it is not barred from constraint validation and should be affected by :invalid pseudo-class. --> <link rel='stylesheet' type='text/css' href='style.css'> <script> function onLoadHandler() { var e = document.getElementById('b'); e.setCustomValidity('foo'); document.documentElement.className=''; } </script> <body onload="onLoadHandler();"> <fieldset disabled> <legend> <button class='invalid' id='b'></button> </legend> </fieldset> </body> </html>