<!DOCTYPE html> <!-- fieldset with one invalid element and a barred for constraint validation element then you remove the second element --> <html class='reftest-wait'> <head> <style> fieldset:valid { display: none; } </style> </head> <script> function onloadHandler() { document.getElementById("fieldset").removeChild(document.getElementById('j')); document.documentElement.className = ''; } </script> <body onload='onloadHandler();'> <fieldset id="fieldset"> <input id='j' required> <input value='foo' readonly> </fieldset> </body> </html>