/* Shared side panels: left "Contents" TOC and right "Topics" navigation.
   Loaded on every page AFTER the theme stylesheet. Themes tint the panels
   by overriding the --panel-* variables; structure and behaviour are
   identical site-wide. Built by tools/site/build.py. */

:root {
    --panel-width: 280px;
    --panel-radius: 16px;
    --panel-bg-a: #FFFFFF;
    --panel-bg-b: #F5F2E8;
    --panel-border: rgba(42, 36, 27, 0.12);
    --panel-shadow: rgba(42, 36, 27, 0.06);
    --panel-heading-font: 'Crimson Pro', serif;
    --panel-heading-color: #2A241B;
    --panel-accent: #B7C7A8;
    --panel-fg: #2A241B;
    --panel-fg-soft: #5C5345;
    --panel-btn-a: #ECE6D2;
    --panel-btn-b: #E0D6BD;
    --panel-btn-fg: #2A241B;
    --panel-chevron-bg: #B7C7A8;
    --panel-chevron-fg: #FFFFFF;
    --panel-hover: rgba(183, 199, 168, 0.25);
    --panel-active-a: rgba(183, 199, 168, 0.35);
    --panel-active-b: rgba(225, 164, 194, 0.15);
    --panel-active-accent: #E1A4C2;
}

.toc-panel, .doc-nav {
    width: var(--panel-width);
    position: sticky;
    top: 2rem;
    align-self: flex-start;
    max-height: calc(100vh - 4rem);
    overflow-y: auto;
    background: linear-gradient(180deg, var(--panel-bg-a) 0%, var(--panel-bg-b) 100%);
    border-radius: var(--panel-radius);
    padding: 1.5rem;
    border: 1px solid var(--panel-border);
    box-shadow: 0 4px 24px var(--panel-shadow);
}

.toc-panel h3, .doc-nav h2 {
    font-family: var(--panel-heading-font);
    font-weight: 600;
    color: var(--panel-heading-color);
    margin: 0 0 1rem 0;
    padding: 0 0 0.75rem 0;
    border-bottom: 3px solid var(--panel-accent);
    border-left: none;
    border-radius: 0;
    background: none;
    font-size: 1.2rem;
    display: flex;
    align-items: center;
    gap: 0.5rem;
}
.doc-nav h2 + ul { margin-bottom: 1rem; }
.toc-panel h3::before { content: "📖"; font-size: 1.05rem; }
.doc-nav h2::before { content: "📚"; font-size: 1.05rem; }

/* ---------- Left panel: per-page contents ---------- */
.toc-panel .toc, .toc-panel .toc ul {
    list-style: none;
    padding-left: 0;
    margin: 0;
}
.toc-panel .toc li { margin: 0; list-style: none; }
.toc-panel .toc-row {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.35rem;
}
.toc-panel .toc a {
    color: var(--panel-fg-soft);
    text-decoration: none;
    border-bottom: none;
    display: block;
    flex: 1;
    padding: 0.3rem 0.5rem;
    border-radius: 6px;
    border-left: 3px solid transparent;
    line-height: 1.45;
    font-size: 0.88rem;
    transition: background-color 0.2s, color 0.2s;
}
.toc-panel .toc a:hover {
    background: var(--panel-hover);
    color: var(--panel-fg);
}
.toc-panel .toc a.active {
    background: linear-gradient(90deg, var(--panel-active-a), var(--panel-active-b));
    border-left-color: var(--panel-active-accent);
    color: var(--panel-fg);
    font-weight: 600;
}
.toc-panel .toc-sub {
    margin: 0.1rem 0 0.35rem 0.9rem !important;
    border-left: 1px solid var(--panel-border);
    padding-left: 0.35rem !important;
}
.toc-panel .toc-sub a { font-size: 0.83rem; }
.toc-panel .toc-sub[hidden] { display: none; }

.toc-toggle {
    background: var(--panel-chevron-bg);
    color: var(--panel-chevron-fg);
    border: none;
    cursor: pointer;
    width: 1.25rem;
    height: 1.25rem;
    border-radius: 50%;
    flex-shrink: 0;
    font-size: 0.65rem;
    line-height: 1;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: transform 0.25s;
}
.toc-toggle[aria-expanded="true"] { transform: rotate(90deg); }

/* ---------- Right panel: shared Topics navigation ---------- */
.doc-nav > ul { padding-left: 0; margin-top: 0; list-style: none; }
.doc-nav li { margin-bottom: 0.5rem; list-style: none; }
.doc-nav li.nav-category {
    margin-top: 0.75rem;
    margin-bottom: 0.5rem;
    border-bottom: none;
    padding-bottom: 0;
}
.doc-nav li.nav-category:first-child { margin-top: 0; }

.doc-nav .nav-toggle {
    background: linear-gradient(135deg, var(--panel-btn-a) 0%, var(--panel-btn-b) 100%);
    border: 1px solid var(--panel-border);
    cursor: pointer;
    width: 100%;
    text-align: left;
    padding: 0.65rem 0.9rem;
    color: var(--panel-btn-fg);
    font: inherit;
    font-weight: 600;
    font-size: 0.92rem;
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 0.5rem;
    border-radius: 10px;
    transition: transform 0.2s, box-shadow 0.2s;
    box-shadow: 0 3px 12px var(--panel-shadow);
}
.doc-nav .nav-toggle:hover {
    transform: translateY(-2px);
    box-shadow: 0 6px 18px var(--panel-shadow);
}
.doc-nav .nav-icon { flex-shrink: 0; }
.doc-nav .nav-label { flex: 1; }
.doc-nav .nav-toggle-icon {
    font-size: 0.7rem;
    transition: transform 0.25s;
    flex-shrink: 0;
    background: var(--panel-chevron-bg);
    color: var(--panel-chevron-fg);
    width: 1.4rem;
    height: 1.4rem;
    border-radius: 50%;
    display: flex;
    align-items: center;
    justify-content: center;
}
.doc-nav .nav-toggle[aria-expanded="true"] .nav-toggle-icon { transform: rotate(90deg); }

.doc-nav .nav-articles {
    padding-left: 1rem;
    margin: 0.5rem 0 0.75rem;
}
.doc-nav .nav-articles li { margin-bottom: 0.2rem; }
.doc-nav .nav-articles[hidden] { display: none; }
.doc-nav .nav-articles:not([hidden]) { display: block; animation: panelSlideDown 0.3s ease; }
@keyframes panelSlideDown {
    from { opacity: 0; transform: translateY(-10px); }
    to { opacity: 1; transform: translateY(0); }
}
.doc-nav .nav-articles a {
    color: var(--panel-fg-soft);
    text-decoration: none;
    font-weight: 500;
    display: block;
    padding: 0.4rem 0.65rem;
    border-radius: 8px;
    border-bottom: none;
    border-left: 3px solid transparent;
    font-size: 0.88rem;
    transition: background-color 0.2s, color 0.2s, transform 0.2s;
}
.doc-nav .nav-articles a:hover {
    background: var(--panel-hover);
    color: var(--panel-fg);
    transform: translateX(3px);
}
.doc-nav .nav-articles .active > a {
    background: linear-gradient(90deg, var(--panel-active-a), var(--panel-active-b));
    color: var(--panel-fg);
    border-left-color: var(--panel-active-accent);
    font-weight: 600;
}

@media (max-width: 1200px) {
    .toc-panel, .doc-nav {
        width: 100%;
        position: static;
        max-height: none;
    }
}