Add custom class to Symfony form label - php

Question

I am building a Symfony 2.7 form and I would like to be able to customise the labels.
At the moment I am able to define the labels using the form builder outlined in the Symfony docs, however I can't see any way to customise the CSS of the label without having to do it on the template.
I know that I would be able to add the CSS class by individually printing the form_label inside of a with my class, but I would prefer to keep it all inside of the form builder.
I've added my current form below for reference.
public function buildForm(FormBuilderInterface $builder, array $options)
{
$builder
->add('dob_day', 'choice', array(
'required' => true,
'choices' => $dobDays,
'mapped' => false,
'attr' => array(
'label' => 'Day',
'class' => 'form-control'
)
))
->add('dob_month', 'choice', array(
'required' => true,
'choices' => $dobMonths,
'mapped' => false,
'attr' => array(
'label' => 'Month',
'class' => 'form-control'
)
))
->add('dob_year', 'choice', array(
'required' => true,
'choices' => $dobYears,
'mapped' => false,
'attr' => array(
'label' => 'Year',
'class' => 'form-control'
)
));
}

Answer 1

If you want to add some CSS to your HTML in the form type, use the style attribute.
->add('dob_year', 'choice', array(
'required' => true,
'choices' => $dobYears,
'mapped' => false,
'attr' => array(
'label' => 'Year',
'class' => 'form-control',
'style' => 'max-width: 4rem;'. // Concat. the styles across lines for clarity.
'border: solid 0.1rem teal;'
)
));
That said,
inside the formType is probably the last place I'd go looking to modify these elements' styles if I was the poor dev who had to maintain this form when you were gone.
While it's possible to add inline CSS here, don't put more than a few lines. If it grows to be more, add a class to some external 'main.css' then add that to your primary template (that all others inherit from) and you'll be able to reuse the styles you've made.
Last thought
This is actually pretty helpful when you're trying to make your formType modular and is why I wanted to answer :) Then I got carried away in a best practice mantra that came off as if this technique doesn't have its place, but it does!