body{
    display: flex;
    flex-direction: column;
}

.principal{
    margin-left: 5%;
    margin-right: 5%;
}

.principal ul{
    margin: 2%;
}

.principal li{
    font-size: 1.2rem;
}

#imagen{
    width: 90%;
    margin-left: auto;
    margin-right: auto;
}