frontend/src/components/Sidebar.css

.sidebar {
    grid-row: 2;
    background: var(--bg-secondary);
    border-right: 1px solid var(--border-subtle);
    display: flex;
    flex-direction: column;
    transition: width var(--transition-base), opacity var(--transition-base);
    overflow: hidden;
}

.sidebar.open {
    width: var(--sidebar-width);
}

.sidebar.closed {
    width: 0;
    border-right: none;
}

.sidebar-content {
    display: flex;
    flex-direction: column;
    height: 100%;
    padding: var(--space-4);
    min-width: var(--sidebar-width);
    overflow-y: auto;
}

/* New Chat Button */
.new-chat-btn {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: var(--space-2);
    width: 100%;
    padding: var(--space-3);
    background: var(--accent-gradient);
    color: white;
    border: none;
    border-radius: var(--radius-md);
    font-size: var(--text-sm);
    font-weight: 600;
    cursor: pointer;
    transition: all var(--transition-fast);
    margin-bottom: var(--space-4);
}

.new-chat-btn:hover {
    opacity: 0.9;
    transform: translateY(-1px);
    box-shadow: var(--shadow-md);
}

/* Section Headers */
.section-header {
    display: flex;
    align-items: center;
    justify-content: space-between;
    margin-bottom: var(--space-3);
}

.section-header.clickable {
    cursor: pointer;
    padding: var(--space-2) 0;
    user-select: none;
}

.section-header.clickable:hover h3 {
    color: var(--text-primary);
}

.section-header h3 {
    font-size: var(--text-xs);
    font-weight: 600;
    color: var(--text-secondary);
    text-transform: uppercase;
    letter-spacing: 0.05em;
    display: flex;
    align-items: center;
    gap: var(--space-2);
}

.chevron {
    transition: transform var(--transition-fast);
}

.chevron.open {
    transform: rotate(90deg);
}

.doc-count {
    font-size: var(--text-xs);
    font-weight: 500;
    color: var(--text-tertiary);
    background: var(--bg-tertiary);
    padding: var(--space-1) var(--space-2);
    border-radius: var(--radius-full);
}

/* Chat History */
.chat-history-section {
    flex: 1;
    display: flex;
    flex-direction: column;
    min-height: 0;
    margin-bottom: var(--space-4);
}

.conversation-list {
    flex: 1;
    display: flex;
    flex-direction: column;
    gap: 2px;
    overflow-y: auto;
}

.empty-conversations {
    display: flex;
    flex-direction: column;
    align-items: center;
    padding: var(--space-6) var(--space-4);
    text-align: center;
    color: var(--text-tertiary);
}

.empty-conversations p {
    font-size: var(--text-sm);
    color: var(--text-secondary);
    margin-bottom: var(--space-1);
}

.empty-conversations span {
    font-size: var(--text-xs);
}

.conversation-item {
    display: flex;
    align-items: center;
    gap: var(--space-2);
    padding: var(--space-2) var(--space-3);
    border-radius: var(--radius-md);
    cursor: pointer;
    transition: all var(--transition-fast);
}

.conversation-item:hover {
    background: var(--bg-tertiary);
}

.conversation-item.active {
    background: var(--bg-elevated);
    border-left: 2px solid var(--accent-primary);
}

.conv-icon {
    color: var(--text-tertiary);
    flex-shrink: 0;
}

.conversation-item.active .conv-icon {
    color: var(--accent-primary);
}

.conv-info {
    flex: 1;
    min-width: 0;
    display: flex;
    flex-direction: column;
}

.conv-title {
    font-size: var(--text-sm);
    color: var(--text-primary);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
    line-height: 1.4;
}

.conv-time {
    font-size: 10px;
    color: var(--text-tertiary);
}

.conv-delete {
    opacity: 0;
    transition: opacity var(--transition-fast);
    flex-shrink: 0;
}

.conversation-item:hover .conv-delete {
    opacity: 1;
}

/* Documents Section */
.documents-section {
    border-top: 1px solid var(--border-subtle);
    padding-top: var(--space-3);
}

/* Upload Zone */
.upload-zone {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--space-4) var(--space-3);
    border: 2px dashed var(--border-subtle);
    border-radius: var(--radius-lg);
    cursor: pointer;
    transition: all var(--transition-base);
    margin-bottom: var(--space-3);
}

.upload-zone:hover {
    border-color: var(--accent-primary);
    background: rgba(99, 102, 241, 0.05);
}

.upload-zone.dragging {
    border-color: var(--accent-primary);
    background: rgba(99, 102, 241, 0.1);
    border-style: solid;
}

.upload-icon {
    width: 40px;
    height: 40px;
    display: flex;
    align-items: center;
    justify-content: center;
    background: var(--bg-glass);
    border-radius: var(--radius-lg);
    color: var(--accent-primary);
    margin-bottom: var(--space-2);
}

.upload-text {
    font-size: var(--text-sm);
    font-weight: 500;
    color: var(--text-primary);
    margin-bottom: var(--space-1);
}

.upload-hint {
    font-size: var(--text-xs);
    color: var(--text-tertiary);
}

/* Upload Progress */
.upload-progress {
    padding: var(--space-3);
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    margin-bottom: var(--space-3);
}

.progress-info {
    display: flex;
    justify-content: space-between;
    margin-bottom: var(--space-2);
}

.progress-name {
    font-size: var(--text-xs);
    color: var(--text-primary);
    max-width: 150px;
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.progress-status {
    font-size: var(--text-xs);
    color: var(--accent-primary);
}

.progress-bar {
    height: 4px;
    background: var(--bg-elevated);
    border-radius: var(--radius-full);
    overflow: hidden;
}

.progress-fill {
    height: 100%;
    background: var(--accent-gradient);
    border-radius: var(--radius-full);
    transition: width var(--transition-base);
}

/* Document List */
.document-list {
    display: flex;
    flex-direction: column;
    gap: var(--space-2);
}

.empty-docs {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    padding: var(--space-4);
    text-align: center;
    color: var(--text-tertiary);
}

.empty-docs p {
    font-size: var(--text-sm);
    color: var(--text-secondary);
    margin-bottom: var(--space-1);
}

.empty-docs span {
    font-size: var(--text-xs);
}

/* Document Item */
.document-item {
    display: flex;
    align-items: center;
    gap: var(--space-3);
    padding: var(--space-2) var(--space-3);
    background: var(--bg-tertiary);
    border-radius: var(--radius-md);
    transition: all var(--transition-fast);
    animation: fadeInUp var(--transition-base) ease;
}

.document-item:hover {
    background: var(--bg-elevated);
}

.doc-icon {
    color: var(--text-tertiary);
    flex-shrink: 0;
}

.doc-info {
    flex: 1;
    min-width: 0;
    display: flex;
    flex-direction: column;
}

.doc-name {
    font-size: var(--text-sm);
    color: var(--text-primary);
    overflow: hidden;
    text-overflow: ellipsis;
    white-space: nowrap;
}

.doc-meta {
    font-size: var(--text-xs);
    color: var(--text-tertiary);
}

.status-icon {
    flex-shrink: 0;
}

.status-icon.uploading {
    color: var(--accent-primary);
}

.status-icon.ready {
    color: var(--success);
}

.status-icon.error {
    color: var(--error);
}

.doc-delete {
    opacity: 0;
    transition: opacity var(--transition-fast);
}

.document-item:hover .doc-delete {
    opacity: 1;
}

/* Clear Data */
.clear-data-section {
    margin-top: auto;
    padding-top: var(--space-4);
    border-top: 1px solid var(--border-subtle);
}

.clear-data-btn {
    width: 100%;
    color: var(--error);
    justify-content: center;
    gap: var(--space-2);
}

.clear-data-btn:hover {
    background: var(--error-bg);
}

@media (max-width: 768px) {
    .sidebar {
        position: fixed;
        top: var(--topnav-height);
        left: 0;
        bottom: 0;
        z-index: 50;
        width: 280px !important;
        transform: translateX(-100%);
    }

    .sidebar.open {
        transform: translateX(0);
        box-shadow: var(--shadow-xl);
    }
}