<!DOCTYPE html> <html> <!-- Test: if one radio in a group has the required attribute and no radio is checked, all radio in the group should suffer from being missing. --> <link rel='stylesheet' type='text/css' href='style.css'> <body> <input class='invalid' id='i1' name='foo' type='radio' required> <input class='invalid' id='i2' name='foo' type='radio'> </body> </html>