.lista ul{
    list-style-type: none;
    text-align: center;
    width: 120px;
    padding: 0;
}

.lista ul li{
    background-color: blue;
    border: 2px solid white;
}
.lista ul li a{
    width: 100px;
    text-decoration: none;
    text-align: center;
    color: white;
    width: 100%;
    display: block;
}

li a:hover{
    outline: 2px solid red;
}

li a:focus{
    outline: 2px solid red;
}

.regresar{
    margin-top: 650px;
    text-align: center;
    font-size: 25px;}
    .back{
        font-family: Verdana, Geneva, Tahoma, sans-serif;
        text-decoration: none;
        color: black;}
        .back:hover{
            text-decoration: underline;
}