Hi there,
This should help:
@media (min-width: 769px) {
.sidebar .menu li > a::after {
content: "";
position: absolute;
right: 0;
left: 50%;
bottom: 0;
-webkit-transform: translateX(-50%);
transform: translateX(-50%);
display: block;
width: 0;
height: 2px;
background-color: currentColor;
transition: 0.3s width ease;
}
.sidebar .menu li.menu-item.current-menu-item > a::after,
.sidebar .menu li.menu-item.current-menu-ancestor > a::after,
.sidebar .menu li.menu-item > a:hover::after {
width: 100%;
}
}
Merry Christmas! ๐