changing the type styling on a dropdown menu

Hi there, I'd like to change the style of the dropdown menu on the site header, so it is different (lighter weight, different colour) to the main navigation style and so the background is semi-transparent. It is currently adopting the style for the main nav. Is there a way to do one or both of these please? attached shows what i currently have and what I would like to achieve. Thanks!

Hi,

What i site url? We can check easier