#left_nav {
    width: 20%;
    float: left;

    margin-top: 3mm;

    padding-left: 5mm;
}
#left_nav a {
    text-decoration: none;
    color: black;
}

#left_nav li {
    margin-bottom: 4mm;
    margin-left: -4mm;
    margin-right: 4mm;
}