Nav links effect

Hi there.
Thanks to this great support forum I was able to add Nav links effect on my menu.
Unfortunately there is something that I need to fix.
I don't know if my request goes beyond the support provided by this forum... Anyway, I try to ask.

I added the follow code and it work well:

/* nav links effect */
.main-navigation .menu > .menu-item > a::after {
    content: "";
    position: absolute;
    right: 0;
    left: 50%;
    bottom: 15px;
    -webkit-transform: translateX(-50%);
    transform: translateX(-50%);

    display: block;
    width: 0;
    height: 2px;

    background-color: currentColor;
    transition: 0.3s width ease;
}
.main-navigation .menu > .menu-item.current-menu-item > a::after,
.main-navigation .menu > .menu-item > a:hover::after {
    width: 80%;
}

The problem is that I'm using a plugin for Mobile menu, and it doesn't work if I use the above code.
The plugin is Superfly Menu.

It is possible to fix?
Thank you.