Hi there,
add this CSS to your site:
@media (min-width: 769px) {
.main-navigation .menu > .menu-item > a::after {
content: "";
display: block;
position: absolute;
left: 20px;
right: 20px;
bottom: 20px;
height: 4px;
-webkit-transform: translateY(-10px);
transform: translateY(-10px);
background-color: currentColor;
opacity: 0;
transition: 0.3s all ease;
pointer-events: none;
}
.main-navigation .menu > .menu-item.current-menu-item > a::after,
.main-navigation .menu > .menu-item.current-menu-ancestor > a::after,
.main-navigation .menu > .menu-item > a:hover::after {
-webkit-transform: translateY(0px);
transform: translateY(0px);
opacity: 1;
}
}