How to assign style class for each select in symfony formtype?

Question

symfony

Goodnight.
Tell me how to connect style classes for each select in the form, the code is below:

public function buildForm(FormBuilderInterface $builder, array $options)
    {
    builder->add('birthday', BirthdayType::class, array(
                            'placeholder' => array(
                                'year' => 'Year', 'month' => 'Month', 'day' => 'Day',
                            ),
                    
                            'label' => 'Дата рождения',
                            'attr' => array('class' => 'select_style')
                ))
}

Answer 1

Solved the problem, for those who come across,

{{ form_widget(form.birthday.day,{'attr': {'class':'name_class_style'}}) }}
{{ form_widget(form.birthday.month,{'attr': {'class':'name_class_style'}}) }}
{{ form_widget(form.birthday.year,{'attr': {'class':'name_class_style'}}) }}