estilo.css

nav {
    display: block;
    position:absolute;
    top: 0px;
    width: 100%;
    background-color: darkslategrey;
}

li {
    position: relative;
    list-style-type: none;
    display: inline;
    margin-right: 30px;
    font-size: 25px;
}

a:link,a:visited {
    color:rgb(255, 255, 255);
    text-decoration: none;
}

a:hover{
    color: orange;
    text-decoration: none;
}

li > ul {
    display: none;
}

li:hover ul {
    display: block;
    position: absolute;
    left: 10px;
    background-color: green;
    margin: 0;
}

li:hover ul li a:link {
    display: block;
    margin-top: 10px;
    margin-right: 10px;
}