anchor.diff:            use_label: false,
             value: form.object.date_of_birth.try(:day),
             placeholder: 'DD',
  -          class: 'js-dob-day t-date-of-birth-day',
  +          class: 'form-dob__input js-dob-day t-date-of-birth-day',
             pattern: '[0-9]*',
             min: 1,
             max: 31,
  
positive.code:           use_label: false,
            value: form.object.date_of_birth.try(:year),
            placeholder: 'YYYY',
            class: 'js-dob-year t-date-of-birth-year',
            pattern: '[0-9]*',
            min: start_year.year,
            max: Date.today.year,
  
negative.code:           use_label: false,
            value: form.object.date_of_birth.try(:month),
            placeholder: 'MM',
            class: 'form-dob__input js-dob-month t-date-of-birth-month',
            pattern: '[0-9]*',
            min: 1,
            max: 12,
  