Change CSS of select

I’m trying to update the CSS of the _dgx_donate_donor_state select field, however the div that contains the text State has an id of _dgx_donate_donor_state as well. So when I use the following
$array[‘elements’][‘_dgx_donate_donor_state’][‘class’] = “form-control”;, the div also gets a class of form-control which is not what I want. I simply want to apply the class to the select field.

Please help!

https://wordpress.org/plugins/seamless-donations/