Hi there,
If you go to Customize > Additional CSS you’ll see the CSS under the /* navigation line effects */
comment.
You can remove it, or update it to apply to top-level menu items only:
@media (min-width: 1024px) {
.main-navigation .main-nav > ul > li > a:before {
position: absolute;
content: '';
width: 1px;
height: 0;
background-color: #607b7d;
left: 50%;
top: -50px;
transform: translateX(-50%);
transition: all .3s ease-out 0s;
}
.main-navigation .main-nav > ul > li:hover > a:before {
height: 50px;
}
.main-navigation .main-nav > ul > li.current-menu-item > a:before {
height: 50px;
width: 1px;
}
}