Current Menu Highlight on Pages Does Not Work

.current-menu-parent or .current-menu-ancestor should do the trick

I tried

.nav .current_page_item a, .current_menu_parent a, .current_menu_ancestor a {text-decoration:overline;}

Unfortunately none of those work.

Could it be because a menu like ‘Contact’ is an actual page, but the other menus are not? (They are not clickable and have an empty link).

hyphens – not underlines:

.current-menu-ancestor

https://codex.www.ads-software.com/Function_Reference/wp_nav_menu#Menu_Item_CSS_Classes

example:

.nav .current-menu-parent a { text-decoration: overline; }
or
#primary-nav .current-menu-ancestor a { text-decoration: overline; }

That seems to have done the trick thanks!

.current_page_item is not present in the nav;

you need to have the .nav in-front of each .current-menu-thingy

.nav .current-menu-parent a {text-decoration:overline;}

It works now thanks, but the sub-menus also get overlined.

I’m trying to target sub-menus with text-decoration:none;

Is there a better way?

I have it fixed thanks to a friend, here is the code I used and see it in effect at my website

/*overline current menu item: for pages*/
.nav .current-menu-item a {
	text-decoration:overline;
}

/*overline current menu parent: for non-linked menu with submenus*/
.nav .current-menu-parent a {
	text-decoration:overline;
}

/*overline menu when hover*/
.nav ul li a.hover,
.nav ul li a:hover {
	text-decoration:overline;
}

/*prevents submenu overline upon hover*/
.nav ul ul li a.hover,
.nav ul ul li a:hover {
	text-decoration:none;
}

/*prevents selected submenu overline*/
.nav .current-menu-parent ul.sub-menu a {
       text-decoration:none;
}