Styling Header, hover effect on sub menus on Squarespace 7.1

Site URL: https://www.cityofhidalgonews.net

I am trying to customize the Header main menu. To add a hover effect on the sub menu....I've tried tech support and they said its not possible. My website - www.cityofhidalgonews.net. I am assuming I need to customize via custom CSS. See attached sample. Right now everything  else works fine, but on desktop and mobile, it is really hard to know where you are clicking since the hover effect is not working on the folder menu....
#tuanphan

Add to Home > Design > Custom CSS

.header-nav-folder-item:hover a {
    text-decoration: underline;
}

Thanks, the underline works, But is it possible a color variation? @tuanphan

11 hours ago, MOSTHEAgency said:

Thanks, the underline works, But is it possible a color variation? @tuanphan

What do you mean?

I'd like to do the same. Can't figure this out in 7.1.