#navbar {
    width: 220px;
    background-color: #4169E1;
    color: #FFFFFF;
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: 1rem;
}

#navbar ul {
    list-style: none;
    width: 100%;
}

#navbar ul li {
    width: 100%;
    margin-bottom: 0.5rem;
}

#navbar ul li a {
    display: block;
    padding: 0.75rem 1rem;
    margin: 0.25rem 0;
    color: #FFFFFF;
    text-decoration: none;
    border-radius: 6px;
    transition: background 0.3s, transform 0.2s;
}

#navbar ul li a:hover,
#navbar ul li a.active {
    background-color: #5A85F2;
    transform: translateX(4px);
}

/* Submenu containers */
.has-submenu {
    position: relative;
}

.submenu {
    max-height: 0; /* hidden by default */
    overflow: hidden;
    display: flex;
    flex-direction: column;
    background-color: #3154B3;
    margin-left: 10px;
    border-left: 2px solid #5A85F2;
    transition: max-height 0.3s ease-out;
}

.submenu li a {
    padding: 0.6rem 1rem;
    font-size: 0.9rem;
}

/* When submenu is open */
.has-submenu.open > .submenu {
    /* Make sure this is big enough to see all links. */
    max-height: 100vh;
    transition: max-height 0.3s ease-in;
}

/* Arrow rotation */
.arrow {
    display: inline-block;
    margin-left: 6px;
    transition: transform 0.3s ease;
}

.has-submenu.open > a .arrow {
    transform: rotate(90deg);
}