:root {
    --bg: #0a1822;
    --bg-elev: #122433;
    --bg-card: #16293a;
    --bg-hover: #1a3146;
    --border: #1f3a52;
    --border-strong: #2c5274;
    --text: #d8e6f0;
    --text-dim: #8aa3b8;
    --accent: #4dd0e1;
    --accent-strong: #80deea;
    --shadow: 0 2px 12px rgba(0, 0, 0, 0.3);
    --radius: 6px;
}

* { box-sizing: border-box; }

html, body {
    margin: 0;
    padding: 0;
    background: var(--bg);
    color: var(--text);
    font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
    font-size: 16px;
    line-height: 1.55;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

button { font-family: inherit; }

.wrap {
    max-width: 1100px;
    margin: 0 auto;
    padding: 0 24px;
}

/* ---------- header / controls ---------- */

.site-header {
    background: linear-gradient(180deg, #0d1f2d 0%, #0a1822 100%);
    border-bottom: 1px solid var(--border);
    padding: 28px 0 20px;
}
.site-header h1 {
    margin: 0 0 6px;
    font-size: 26px;
    letter-spacing: 1px;
    color: var(--accent-strong);
    text-transform: uppercase;
}
.tagline {
    margin: 0 0 6px;
    color: var(--text-dim);
    font-size: 14px;
}
.meta {
    margin: 0;
    color: var(--text-dim);
    font-size: 13px;
}

.controls {
    background: var(--bg-elev);
    border-bottom: 1px solid var(--border);
    padding: 14px 0;
    position: sticky;
    top: 0;
    z-index: 10;
    box-shadow: var(--shadow);
}
.controls input[type="search"] {
    width: 100%;
    padding: 10px 14px;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    color: var(--text);
    font-size: 15px;
    outline: none;
}
.controls input[type="search"]:focus {
    border-color: var(--accent);
}
.filters {
    display: flex;
    flex-wrap: wrap;
    gap: 16px;
    align-items: center;
    margin-top: 10px;
    font-size: 14px;
    color: var(--text-dim);
}
.link-btn {
    background: none;
    border: none;
    color: var(--accent);
    cursor: pointer;
    padding: 4px 0;
    font-size: 14px;
}
.link-btn:hover { text-decoration: underline; }
.toggle {
    display: flex;
    align-items: center;
    gap: 6px;
    cursor: pointer;
}
.result-count {
    margin-left: auto;
    color: var(--text-dim);
}

main {
    padding: 20px 24px 64px;
}

/* ---------- tree ---------- */

.tree, .tree-children {
    list-style: none;
    margin: 0;
    padding: 0;
}
.tree-children {
    margin-left: 14px;
    padding-left: 12px;
    border-left: 1px solid var(--border);
}
.tree-category,
.tree-leaf {
    margin: 4px 0;
}

.category-header,
.leaf-header {
    display: flex;
    align-items: center;
    gap: 8px;
    width: 100%;
    text-align: left;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    color: var(--text);
    padding: 10px 14px;
    font-size: 15px;
    cursor: pointer;
    transition: background 100ms, border-color 100ms;
}
.category-header:hover,
.leaf-header:hover {
    background: var(--bg-hover);
    border-color: var(--border-strong);
}
.category-header {
    background: linear-gradient(180deg, #1a334a 0%, #142a3d 100%);
    color: var(--accent-strong);
    font-weight: 600;
}
.tree-category.open > .category-header {
    border-color: var(--accent);
    background: linear-gradient(180deg, #1f3d56 0%, #173248 100%);
}

.chevron {
    display: inline-block;
    width: 14px;
    color: var(--accent);
    font-size: 12px;
    flex-shrink: 0;
}

.category-name {
    flex: 1;
}
.category-count {
    color: var(--text-dim);
    font-size: 13px;
    font-weight: normal;
    background: rgba(0, 0, 0, 0.25);
    padding: 1px 8px;
    border-radius: 999px;
}

.leaf-title {
    flex: 1;
}

.tree-leaf.is-category-header > .leaf-header {
    border-left: 3px solid var(--accent);
}

/* ---------- entry detail (when expanded) ---------- */

.entry-detail {
    margin: 6px 0 12px 22px;
    padding: 16px 18px;
    background: var(--bg-card);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    position: relative;
}

.entry-image {
    float: right;
    width: 200px;
    max-width: 40%;
    height: auto;
    margin: 0 0 8px 16px;
    border-radius: var(--radius);
    border: 1px solid var(--border);
    background: var(--bg);
    display: block;
}

.entry-body {
    white-space: pre-wrap;
    color: var(--text);
    font-size: 15px;
    line-height: 1.6;
}
.entry-body::after {
    content: '';
    display: block;
    clear: both;
}

.entry-meta {
    margin-top: 12px;
    padding-top: 10px;
    border-top: 1px solid var(--border);
    display: flex;
    flex-wrap: wrap;
    gap: 12px;
    align-items: center;
    color: var(--text-dim);
    font-size: 12px;
}
.entry-breadcrumb {
    flex: 1;
    min-width: 0;
}
.entry-id {
    font-family: ui-monospace, "Cascadia Mono", Consolas, monospace;
    color: var(--text-dim);
    opacity: 0.7;
}

mark {
    background: rgba(77, 208, 225, 0.25);
    color: var(--accent-strong);
    padding: 0 2px;
    border-radius: 2px;
}

.empty {
    color: var(--text-dim);
    text-align: center;
    padding: 40px 0;
}

/* ---------- nav buttons (header) ---------- */

.header-nav {
    margin-top: 12px;
    display: flex;
    flex-wrap: wrap;
    gap: 10px;
}
.nav-btn {
    display: inline-flex;
    align-items: center;
    gap: 6px;
    padding: 7px 14px;
    background: var(--bg-card);
    border: 1px solid var(--border-strong);
    border-radius: var(--radius);
    color: var(--accent-strong);
    font-size: 13px;
    font-weight: 600;
    letter-spacing: 0.3px;
    text-decoration: none;
    transition: background 100ms, border-color 100ms, color 100ms;
}
.nav-btn:hover {
    background: var(--bg-hover);
    border-color: var(--accent);
    color: var(--accent-strong);
    text-decoration: none;
}

/* ---------- footer ---------- */

.site-footer {
    border-top: 1px solid var(--border);
    background: var(--bg-elev);
    color: var(--text-dim);
    font-size: 12px;
    padding: 20px 0;
    text-align: center;
}

/* ---------- timeline page (markdown rendering) ---------- */

.timeline-page main {
    padding: 28px 24px 64px;
}

.timeline-page .back-link {
    color: var(--accent);
    font-weight: 600;
}
.timeline-page .meta-sep {
    margin: 0 8px;
    color: var(--border-strong);
}
.timeline-page .meta-warn {
    color: var(--text-dim);
    font-style: italic;
}

.markdown-body {
    color: var(--text);
    font-size: 16px;
    line-height: 1.7;
    max-width: 860px;
    margin: 0 auto;
}

.markdown-body .loading {
    color: var(--text-dim);
    text-align: center;
    padding: 40px 0;
}

.markdown-body h1,
.markdown-body h2,
.markdown-body h3,
.markdown-body h4,
.markdown-body h5,
.markdown-body h6 {
    color: var(--accent-strong);
    font-weight: 600;
    line-height: 1.25;
    margin: 1.8em 0 0.6em;
}
.markdown-body h1 {
    font-size: 28px;
    letter-spacing: 0.5px;
    border-bottom: 1px solid var(--border-strong);
    padding-bottom: 10px;
    margin-top: 0.4em;
}
.markdown-body h2 {
    font-size: 22px;
    border-bottom: 1px solid var(--border);
    padding-bottom: 6px;
    margin-top: 2.2em;
}
.markdown-body h3 {
    font-size: 19px;
    color: var(--accent);
}
.markdown-body h4 {
    font-size: 16px;
    color: var(--text);
    text-transform: uppercase;
    letter-spacing: 0.5px;
}

.markdown-body p {
    margin: 0.8em 0;
}

.markdown-body a {
    color: var(--accent);
    text-decoration: none;
    border-bottom: 1px dotted var(--border-strong);
}
.markdown-body a:hover {
    color: var(--accent-strong);
    border-bottom-color: var(--accent);
    text-decoration: none;
}

.markdown-body strong {
    color: var(--accent-strong);
    font-weight: 600;
}
.markdown-body em {
    color: var(--text);
}

.markdown-body ul,
.markdown-body ol {
    margin: 0.8em 0;
    padding-left: 28px;
}
.markdown-body li {
    margin: 0.3em 0;
}
.markdown-body li > ul,
.markdown-body li > ol {
    margin: 0.3em 0;
}

.markdown-body blockquote {
    margin: 1.2em 0;
    padding: 12px 18px;
    background: var(--bg-card);
    border-left: 3px solid var(--accent);
    border-radius: 0 var(--radius) var(--radius) 0;
    color: var(--text);
}
.markdown-body blockquote p {
    margin: 0.4em 0;
}
.markdown-body blockquote p:first-child { margin-top: 0; }
.markdown-body blockquote p:last-child  { margin-bottom: 0; }

.markdown-body code {
    font-family: ui-monospace, "Cascadia Mono", Consolas, monospace;
    font-size: 0.88em;
    background: rgba(0, 0, 0, 0.3);
    color: var(--accent-strong);
    padding: 1px 6px;
    border-radius: 4px;
    border: 1px solid var(--border);
    white-space: nowrap;
}
.markdown-body pre {
    margin: 1em 0;
    padding: 14px 16px;
    background: var(--bg);
    border: 1px solid var(--border);
    border-radius: var(--radius);
    overflow-x: auto;
}
.markdown-body pre code {
    background: none;
    border: none;
    padding: 0;
    color: var(--text);
    white-space: pre;
}

.markdown-body hr {
    border: none;
    border-top: 1px solid var(--border-strong);
    margin: 2em 0;
}

.markdown-body table {
    width: 100%;
    border-collapse: collapse;
    margin: 1.2em 0;
    font-size: 14px;
}
.markdown-body th,
.markdown-body td {
    padding: 8px 12px;
    text-align: left;
    border: 1px solid var(--border);
    vertical-align: top;
}
.markdown-body th {
    background: var(--bg-elev);
    color: var(--accent-strong);
    font-weight: 600;
}
.markdown-body tr:nth-child(even) td {
    background: rgba(255, 255, 255, 0.015);
}

/* ---------- citation links ---------- */

.markdown-body a.citation {
    border-bottom: none;
    padding: 0;
}
.markdown-body a.citation > code {
    cursor: pointer;
    transition: background 100ms, border-color 100ms, color 100ms;
}
.markdown-body a.citation:hover > code {
    background: rgba(77, 208, 225, 0.18);
    border-color: var(--accent);
    color: var(--accent-strong);
}

/* ---------- responsive ---------- */

@media (max-width: 600px) {
    .site-header h1 { font-size: 22px; }
    main { padding: 16px 14px 48px; }
    .filters { font-size: 13px; }
    .result-count { margin-left: 0; width: 100%; }

    .tree-children {
        margin-left: 8px;
        padding-left: 8px;
    }
    .entry-detail {
        margin-left: 0;
    }
    .entry-image {
        float: none;
        width: 100%;
        max-width: 100%;
        margin: 0 0 12px 0;
    }
}