#callback_form { max-width: 400px; margin: 0 auto; position: relative; }

#callback_form .wpcf7-validation-errors, 
#callback_form .wpcf7-not-valid-tip { color: #f00; }

#callback_form .wpcf7-mail-sent-ok { color: #398f14; }

#callback_form .screen-reader-response { display: none; }