:root {
    --nav-width: 100px;
}
.side-nav {
    position: fixed;
    margin-top: 90px;
    width: var(--nav-width);
    background-color: #004a99;
    border-right: 1px solid #aaccee;
    color: white;
    height: calc(100vh - 90px);
    overflow-y: auto;
}

.side-nav ul {
    list-style: none;
    padding: 0;
    margin: 0;
}

.side-nav li {
    margin: 10px 0;
    text-align: center;
}

.side-nav a {
    color: white;
    text-decoration: none;
    display: block;
    padding: 10px 0;
}
.side-nav a.active {
    font-weight: bold;
    color: var(--accent-color);
}

.side-nav a:hover {
    background-color: #003366;
}