Hovered animation

Hi, so I'm working on a website and there is no option for making animation to underline the elements whenever the cursor move. It will be like the word "Marketing" in the file I attached. Any help would be great. Thank you in advance :)

Which elements? and can you share link to your site?

yes, the password is 123 https://penguin-tunny-d26f.squarespace.com/config/settings
So the photography section, when I move the cursor to that one. Other sections will be automatically showed. In this case, I want to have the section underlined whenever I move the cursor because it's quite unclear to know which one I'm choosing. 
Cám ơn bác trước nha

On 7/23/2020 at 3:25 AM, timegrocery said:

yes, the password is 123 https://penguin-tunny-d26f.squarespace.com/config/settings
So the photography section, when I move the cursor to that one. Other sections will be automatically showed. In this case, I want to have the section underlined whenever I move the cursor because it's quite unclear to know which one I'm choosing. 
Cám ơn bác trước nha

You mean Food, People... items? Add to Home > Design > Custom CSS

.header-nav-folder-item a:hover {
    border-bottom: 1px solid currentColor;
}