HOW TO SPECIFY CSS

Hi...
i used paulca-phone_codes plugin for country code.and it works.
<%= f.select :country_code, PhoneCode.options_for_select(:prefix)%>
what i want to know is how to apply css class for this.when i tried like
below it doesnot work
<%= f.select :country_code, PhoneCode.options_for_select(:prefix),
{:class => "mystyle" }%>

Because select takes two hashes of options. The first is for options
for select itself, the second is for html options. You're sticking
your html options in the first hash.

Fred