HTML - Transicion y Hover en css

body{

    margin: 0;

    padding: 0;

    display: flex;

    justify-content: center;

    align-items: center;

    min-height: 100vh;

    font-family: 'Poppins', sans-serif;

}

ul{

    position: relative;

    margin: 0;

    padding: 0;

}

ul li{

    list-style: none;

    margin: 0;

    font-size: 1.5em;

}

ul li a{

    position: relative;

    color: #ddd;

    text-decoration: none;

    font-weight: 700;

    transition: 0.5s ease-in-out;

}

ul li a:hover {

    color:Black;

}

ul li a:before{

    content: attr(data-text);

    position: absolute;

    top: -2px;

    width: 100%;

    color: #262626;

    overflow: hidden;

    white-space: nowrap;

}

ul:hover li a:before{

    width: 0;

}

ul li:hover a:before{

    width: 100%;

}