<!DOCTYPE html>
<html class="reftest-wait">
<link rel='stylesheet' type='text/css' href='style.css'>
<body onload="if (!document.getElementById('i').matches(':valid')) {
document.body.textContent='FAIL';
} else {
document.body.textContent='SUCCESS';
}
document.documentElement.className='';">
<input id='i' type='radio' checked required>
</body>
</html>