.nav-link{
    transition: all 0.2s;
}
.nav-link:hover::after{

}
.nav-link::after{
    transition: all 0.2s;
}
.nav-link:hover::after{
    content: "";
    opacity: 1;
    height: 2px;
    width: 100%;
    background-color: greenyellow;
    position: absolute;
    bottom: 0;
    left: 0;
}
.nav-link:hover::after{
    opacity: 1;
}