.toc-item {
    border-left: 2px solid transparent;
    transition: all 0.3s ease;
}
.toc-item:hover, .toc-item.active {
    border-left: 2px solid #7c3aed;
    background-color: rgba(124, 58, 237, 0.05);
}
.toc-item.active a {
    color: #7c3aed;
    font-weight: 500;
}

.dropdown {
    opacity: 0;
    visibility: hidden;
    transform: translateY(10px);
    transition: opacity 0.3s ease, transform 0.3s ease, visibility 0.3s;
}

.dropdown.active {
    opacity: 1;
    visibility: visible;
    transform: translateY(0);
}