/**
 * Tree Navigation Styles — improved
 */

/* ── Sidebar scrollbar ────────────────────────────────────────────────────── */
.sidebar {
    scrollbar-width: thin;
    scrollbar-color: var(--border-light) transparent;
}
.sidebar::-webkit-scrollbar       { width: 4px; }
.sidebar::-webkit-scrollbar-track { background: transparent; }
.sidebar::-webkit-scrollbar-thumb { background: var(--border-light); border-radius: 4px; }

/* ── Search box ───────────────────────────────────────────────────────────── */
.sidebar__header {
    padding: var(--spacing-md) var(--spacing-md) var(--spacing-sm);
    border-bottom: 1px solid var(--border-color);
    position: relative;
}

.sidebar__header::before {
    content: '';
    position: absolute;
    left: calc(var(--spacing-md) + 10px);
    top: 50%;
    transform: translateY(-58%);
    width: 14px;
    height: 14px;
    background-image: url("data:image/svg+xml,%3Csvg xmlns='http://www.w3.org/2000/svg' width='14' height='14' viewBox='0 0 24 24' fill='none' stroke='%23808080' stroke-width='2'%3E%3Ccircle cx='11' cy='11' r='8'/%3E%3Cpath d='m21 21-4.35-4.35'/%3E%3C/svg%3E");
    background-repeat: no-repeat;
    pointer-events: none;
}

.search-box {
    width: 100%;
    padding: 0.45rem 0.75rem 0.45rem 2rem;
    background-color: var(--bg-primary);
    border: 1px solid var(--border-color);
    border-radius: 20px;
    color: var(--text-primary);
    font-size: 0.85rem;
    transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

.search-box::placeholder { color: var(--text-muted); }

.search-box:focus {
    outline: none;
    border-color: var(--accent-blue);
    box-shadow: 0 0 0 3px rgba(59, 130, 246, 0.12);
}

/* ── Tree wrapper ─────────────────────────────────────────────────────────── */
.tree-navigation {
    padding: var(--spacing-sm) 0;
}

/* ── Tree Node base ───────────────────────────────────────────────────────── */
.tree-node {
    margin-bottom: 1px;
}

.tree-node__header {
    display: flex;
    align-items: center;
    gap: 6px;
    padding: 5px var(--spacing-sm);
    border-radius: 6px;
    cursor: pointer;
    transition: background 0.12s ease, color 0.12s ease;
    color: var(--text-primary);
    text-decoration: none;
    user-select: none;
    position: relative;
    margin: 0 6px;
}

.tree-node__header:hover {
    background-color: var(--bg-hover);
}

/* Active state — left accent bar + subtle tint */
.tree-node__header--active {
    background-color: rgba(59, 130, 246, 0.14);
    color: #93c5fd;
}

.tree-node__header--active::before {
    content: '';
    position: absolute;
    left: -6px;
    top: 20%;
    bottom: 20%;
    width: 3px;
    background: var(--accent-blue);
    border-radius: 0 3px 3px 0;
}

.tree-node__header--active .tree-node__count {
    background-color: rgba(59, 130, 246, 0.25);
    color: #93c5fd;
}

/* ── Root-level categories ────────────────────────────────────────────────── */
.tree-node--root {
    margin-top: 4px;
}

.tree-node--root:not(:first-child) {
    border-top: 1px solid var(--border-color);
    padding-top: 4px;
    margin-top: 4px;
}

.tree-node--root > .tree-node__header .tree-node__label {
    font-size: 0.875rem;
    font-weight: 600;
    color: var(--text-primary);
}

/* ── Toggle button ────────────────────────────────────────────────────────── */
.tree-node__toggle {
    background: none;
    border: none;
    padding: 0;
    margin: 0;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    width: 18px;
    height: 18px;
    flex-shrink: 0;
    color: var(--text-muted);
    border-radius: 3px;
    transition: color 0.12s ease, background 0.12s ease;
}

.tree-node__toggle:hover {
    color: var(--text-secondary);
    background: rgba(255, 255, 255, 0.06);
}

.tree-node__icon {
    transition: transform 0.18s ease;
}

.tree-node__icon--expanded {
    transform: rotate(90deg);
}

.tree-node__spacer {
    display: inline-block;
    width: 18px;
    flex-shrink: 0;
}

/* ── Category icon (emoji) ────────────────────────────────────────────────── */
.tree-node__icon-emoji {
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 14px;
    line-height: 1;
    width: 18px;
    flex-shrink: 0;
}

/* ── Category icon (SVG folder) ───────────────────────────────────────────── */
.tree-node__icon-folder,
.tree-node__icon-file {
    display: flex;
    align-items: center;
    color: var(--text-muted);
    flex-shrink: 0;
}

.tree-node--root > .tree-node__header .tree-node__icon-folder,
.tree-node--root > .tree-node__header .tree-node__icon-emoji {
    color: var(--accent-blue);
}

/* ── Label ────────────────────────────────────────────────────────────────── */
.tree-node__label {
    flex: 1;
    font-size: 0.85rem;
    font-weight: 500;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    min-width: 0;
}

.tree-node--article .tree-node__label {
    font-size: 0.82rem;
    font-weight: 400;
    color: var(--text-secondary);
}

/* ── Count badge ──────────────────────────────────────────────────────────── */
.tree-node__count {
    background-color: rgba(255, 255, 255, 0.07);
    color: var(--text-muted);
    padding: 1px 6px;
    border-radius: 10px;
    font-size: 0.72rem;
    font-weight: 600;
    flex-shrink: 0;
    letter-spacing: 0.02em;
}

/* ── Video badge ──────────────────────────────────────────────────────────── */
.tree-node__video-badge {
    font-size: 0.8rem;
    flex-shrink: 0;
}

/* ── Children container ───────────────────────────────────────────────────── */
.tree-node__children {
    margin-left: 14px;
    padding-left: 10px;
    border-left: 1px solid rgba(255, 255, 255, 0.07);
    animation: treeSlideDown 0.15s ease;
}

/* ── Indentation levels ───────────────────────────────────────────────────── */
.tree-node--level-0 { margin-left: 0; }
.tree-node--level-1 { margin-left: 0; }
.tree-node--level-2 { margin-left: 0; }
.tree-node--level-3 { margin-left: 0; }

/* ── Article items (compact) ──────────────────────────────────────────────── */
.tree-node--article .tree-node__header {
    padding-top: 4px;
    padding-bottom: 4px;
}

.tree-node--article .tree-node__header:hover .tree-node__label {
    color: var(--text-primary);
}

.tree-node--article .tree-node__header--active .tree-node__label {
    color: #93c5fd;
}

/* ── Category link ────────────────────────────────────────────────────────── */
.tree-node__category-link {
    display: flex;
    align-items: center;
    flex: 1;
    text-decoration: none;
    color: inherit;
    gap: 6px;
    min-width: 0;
}

/* ── Animations ───────────────────────────────────────────────────────────── */
@keyframes treeSlideDown {
    from { opacity: 0; transform: translateY(-4px); }
    to   { opacity: 1; transform: translateY(0); }
}

/* ── Search Results ───────────────────────────────────────────────────────── */
.tree-search-results {
    padding: var(--spacing-sm);
}

.tree-search-header {
    display: flex;
    justify-content: space-between;
    align-items: center;
    padding: var(--spacing-xs) var(--spacing-xs);
    margin-bottom: var(--spacing-sm);
    font-size: 0.78rem;
    color: var(--text-muted);
    border-bottom: 1px solid var(--border-color);
}

.tree-search-clear {
    background: none;
    border: none;
    color: var(--accent-blue);
    cursor: pointer;
    font-size: 0.78rem;
    padding: 2px 6px;
    border-radius: 4px;
    transition: background 0.12s ease;
}

.tree-search-clear:hover {
    background: rgba(59, 130, 246, 0.1);
}

.tree-search-result {
    margin-bottom: 2px;
}

.tree-search-result__link {
    display: flex;
    align-items: flex-start;
    gap: var(--spacing-sm);
    padding: 6px 8px;
    border-radius: var(--border-radius);
    transition: background 0.12s ease;
    text-decoration: none;
    color: var(--text-primary);
    cursor: pointer;
}

.tree-search-result__link:hover {
    background-color: var(--bg-hover);
}

.tree-search-result__icon {
    color: var(--text-muted);
    flex-shrink: 0;
    margin-top: 2px;
}

.tree-search-result__title {
    font-size: 0.83rem;
    font-weight: 500;
    margin-bottom: 1px;
}

.tree-search-result__title mark {
    background-color: rgba(245, 158, 11, 0.3);
    color: var(--accent-yellow);
    padding: 0 2px;
    border-radius: 2px;
}

.tree-search-result__meta {
    font-size: 0.75rem;
    color: var(--text-muted);
}

.tree-search-empty {
    padding: var(--spacing-lg);
    text-align: center;
    color: var(--text-muted);
    font-size: 0.85rem;
}

/* ── Error state ──────────────────────────────────────────────────────────── */
.tree-error {
    padding: var(--spacing-lg);
    text-align: center;
    color: var(--accent-red);
    font-size: 0.85rem;
}

.tree-error button {
    margin-top: var(--spacing-md);
    padding: var(--spacing-sm) var(--spacing-md);
    background-color: var(--accent-blue);
    color: white;
    border: none;
    border-radius: var(--border-radius);
    cursor: pointer;
    font-size: 0.85rem;
}

/* ── Loading state ────────────────────────────────────────────────────────── */
.tree-loading {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 0.75rem;
    padding: var(--spacing-xl);
    color: var(--text-muted);
    font-size: 0.85rem;
}

.tree-loading::before {
    content: '';
    width: 20px;
    height: 20px;
    border: 2px solid var(--border-light);
    border-top-color: var(--accent-blue);
    border-radius: 50%;
    animation: treeSpin 0.7s linear infinite;
}

@keyframes treeSpin {
    to { transform: rotate(360deg); }
}

/* ── Mobile ───────────────────────────────────────────────────────────────── */
@media (max-width: 640px) {
    .tree-node__header {
        padding: 6px var(--spacing-sm);
    }
    .tree-node__label {
        font-size: 0.82rem;
    }
    .tree-node__children {
        margin-left: 10px;
        padding-left: 8px;
    }
}