body{
    background-color: orange;
}




nav ul li{
    display: inline-block;
    list-style: none;
    margin: 10px 10px;
}

nav ul li a{
    color: #050404;
    text-decoration: none;
    font-size: 18px;
    position: relative;
    font-family: 'system-ui', sans-serif;
}

nav ul li a::after{
    content:'';
    width: 0;
    height: 3px;
    background: #050404;
    position: absolute;
    left: 0;
    bottom: -6px;
    transition: 0.4s;
}

nav ul li a:hover::after{
    width: 100%;
}