How to add drop shadow to navigation menu text

I am trying to add drop shadow to the navigation menu text so it is readable on top of the background image. I have tired to add some code to the Custom CSS but it is not working. https://www.successfulfilipina.com/

You can use this to Custom CSS box

nav.header-nav-list {
    box-shadow: 3px 3px 3px 5px #000;
}

This added a box drop shadow that is not what I want. I want the text to have a drop shadow.

If text itself, use code like this

div.header-nav-item a {
    text-shadow: 3px 3px 5px #000;
}