.lesson-topic {
    font-weight: 600;
    font-size: 13px;
    color: #1a1a1a;
    padding: 10px 12px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    border-radius: 6px;
    margin: 8px 4px 4px 4px;
    transition: background-color 0.2s ease;
}

.lesson-topic:hover {
    background-color: rgba(0, 0, 0, 0.05);
}

.lesson-folder {
    font-weight: 500;
    font-size: 12px;
    color: #4a4a4a;
    padding: 8px 12px 8px 24px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    border-radius: 6px;
    margin: 4px 4px;
    transition: background-color 0.2s ease;
}

.lesson-folder:hover {
    background-color: rgba(0, 0, 0, 0.03);
}

.lesson-item {
    font-weight: 400;
    font-size: 12px;
    color: #333;
    padding: 8px 12px 8px 36px;
    cursor: pointer;
    display: flex;
    align-items: center;
    gap: 8px;
    border-radius: 6px;
    margin: 2px 2px;
    border: none;
    background: none;
    text-align: left;
    width: 100%;
    transition: background-color 0.2s ease;
    box-sizing: border-box;
    position: relative;
}

.lesson-item:hover {
    background-color: rgba(0, 0, 0, 0.04);
}

.lesson-item::after {
    content: attr(data-lesson-type);
    position: absolute;
    right: 10px;
    top: 50%;
    transform: translateY(-50%);
    background-color: #333;
    color: white;
    padding: 4px 8px;
    border-radius: 4px;
    font-size: 11px;
    white-space: nowrap;
    opacity: 0;
    pointer-events: none;
    transition: opacity 0.2s ease;
    z-index: 100;
}

.lesson-item:hover::after {
    opacity: 1;
}

.lesson-chevron {
    height: 14px;
    width: 14px;
    transition: transform 0.2s ease;
    flex-shrink: 0;
}

.lesson-chevron.rotated {
    transform: rotate(-90deg);
}

.sidebar-content-item-icon {
    height: 24px;
    width: 24px;
    flex-shrink: 0;
}

.lesson-topic-title,
.lesson-folder-title,
.lesson-item-title {
    flex: 1;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
}

.lesson-item-icon {
    height: 16px;
    width: 16px;
    filter: invert(43%) sepia(0%) saturate(0%) hue-rotate(338deg) brightness(91%) contrast(85%);
    flex-shrink: 0;
}

.lesson-children {
    max-height: 2000px;
    overflow: hidden;
    transition: max-height 0.3s ease;
}

.lesson-children.collapsed {
    max-height: 0;
}

.sidebar-no-lessons {
    margin-top: 20px;
    margin-left: 7%;
    font-size: 14px;
    color: #999;
    font-style: italic;
}