/* ============================================================================
   Knowledge Hub — canonical 3-column doc layout for content sites.

   Inspired by docs.obsidian.md: sidebar nav (left, sticky) + article column
   (centre, line-length-constrained) + on-this-page TOC (right, sticky).
   Translated into Marbl tokens.

   Use for: Thou Art That, future Marbl knowledge-hub microsites,
   informational pages, repo doc pages.

   Spec: ./knowledge-hub.md  ·  Preview: ./preview.html
   Settled: 28 April 2026

   Class prefix: .kh-*
   Loads alongside canonical site-header / menu / site-footer / cookie-consent.
   Consumer must include these via marbl-core.css bundle (or individual links).
   ============================================================================ */

/* Smooth-scroll anchor jumps from the right-side TOC.
   Combines with scroll-margin-top on h2/h3 to avoid sticky-header tuck. */
html { scroll-behavior: smooth; }
@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
}

/* === Page shell — main becomes the 3-col grid container === */

.kh-shell {
  display: grid;
  grid-template-columns: minmax(0, var(--kh-sidebar-w, 260px)) minmax(0, 1fr) minmax(0, var(--kh-toc-w, 240px));
  gap: var(--gap-md, 40px);
  max-width: var(--kh-shell-max, 1600px);
  margin: 0 auto;
  padding: var(--gap-md, 40px);
  align-items: start;
  position: relative;
}


/* Sidebar scrollbar override — thin + subtle grey, scoped to KH
   sidebar only. Page-level (html) scrollbar stays canonical ember
   per marbl-v2.css. Locked 30 Apr 2026. */
.kh-sidebar,
.kh-toc {
  scrollbar-width: thin;
  scrollbar-color: var(--marbl-white-15, rgba(255, 255, 255, 0.15)) transparent;
}
.kh-sidebar::-webkit-scrollbar,
.kh-toc::-webkit-scrollbar {
  width: 6px;
  height: 6px;
}
.kh-sidebar::-webkit-scrollbar-track,
.kh-toc::-webkit-scrollbar-track {
  background: transparent;
}
.kh-sidebar::-webkit-scrollbar-thumb,
.kh-toc::-webkit-scrollbar-thumb {
  background: var(--marbl-white-15, rgba(255, 255, 255, 0.15));
  border-radius: var(--radius-full, 9999px);
}
.kh-sidebar::-webkit-scrollbar-thumb:hover,
.kh-toc::-webkit-scrollbar-thumb:hover {
  background: var(--marbl-white-30, rgba(255, 255, 255, 0.3));
}

/* === Sidebar (left) — sticky tree nav + search === */

.kh-sidebar {
  position: sticky;
  top: var(--gap-md, 40px);
  max-height: calc(100dvh - var(--gap-md, 40px) * 2);
  overflow-y: auto;
  padding-right: var(--gap-xs, 10px);
  font-family: var(--font-body, 'Inter', sans-serif);
  font-size: var(--text-sm, 13px);
}

/* Section heading — used twice: above search and above contents.
   Ember accent. Consistent 20px gap below to the following content
   (search field or nav) so both stretches breathe equally. */
.kh-sidebar__heading {
  font-family: var(--font-heading, 'Urbanist', sans-serif);
  font-size: var(--text-xs, 11px);
  font-weight: var(--font-semibold, 600);
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--marbl-ember, #F35226);
  line-height: 1.2;
  margin: 0 0 var(--gap-sm, 20px) 0;
}
.kh-sidebar__heading:not(:first-child) { margin-top: var(--gap-md, 40px); }

/* Search input — line style (bottom border only), matches Marbl input convention.
   Underline lights ember on focus. */
.kh-sidebar__search {
  display: block;
  width: 100%;
  margin: 0 0 var(--gap-md, 40px) 0;
  padding: var(--gap-xs, 10px) 0;
  background: transparent;
  border: 0;
  border-bottom: 1px solid var(--marbl-white-15, rgba(255, 255, 255, 0.15));
  border-radius: 0;
  color: var(--marbl-white, #ffffff);
  font: inherit;
  font-size: var(--text-base, 15px);
  transition: border-color 0.15s ease;
  -webkit-appearance: none;
  appearance: none;
}

.kh-sidebar__search::placeholder { color: var(--marbl-white-40, rgba(255, 255, 255, 0.4)); }
.kh-sidebar__search:focus { outline: none; border-bottom-color: var(--marbl-ember, #F35226); }
.kh-sidebar__search::-webkit-search-cancel-button { -webkit-appearance: none; }

/* Search field wrap — provides positioning context for the absolute-
   floated results panel so it overlays content instead of pushing
   the nav (and the sidebar's own scrollbar) down. */
.kh-sidebar__search-field {
  position: relative;
  margin: 0 0 var(--gap-md, 40px) 0;
}
.kh-sidebar__search-field .kh-sidebar__search { margin-bottom: 0; }

/* Search results panel — position:fixed escapes the sidebar's overflow:auto
   so the panel never gets clipped or triggers a sidebar scrollbar. JS
   computes top/left/width from the input's bounding rect on each render
   and on viewport scroll/resize. */
.kh-search-results {
  display: none;
  position: fixed;
  z-index: 100;
  padding: var(--gap-2xs, 6px);
  background: var(--marbl-charcoal-light, #1d1a1b);
  border: 1px solid var(--marbl-white-08, rgba(255, 255, 255, 0.08));
  border-radius: var(--radius, 10px);
  max-height: 50vh;
  overflow-y: auto;
  /* Themed scrollbar — Firefox + WebKit. Tracks the panel bg. */
  scrollbar-color: var(--marbl-white-15, rgba(255, 255, 255, 0.15)) var(--marbl-charcoal-light, #1d1a1b);
  scrollbar-width: thin;
}
.kh-search-results.is-open { display: block; }
.kh-search-results::-webkit-scrollbar { width: 8px; }
.kh-search-results::-webkit-scrollbar-track { background: var(--marbl-charcoal-light, #1d1a1b); }
.kh-search-results::-webkit-scrollbar-thumb {
  background: var(--marbl-white-15, rgba(255, 255, 255, 0.15));
  border-radius: var(--radius-sm, 4px);
}
.kh-search-results::-webkit-scrollbar-thumb:hover {
  background: var(--marbl-white-30, rgba(255, 255, 255, 0.3));
}

.kh-search-results__item {
  display: block;
  padding: var(--gap-xs, 10px) var(--gap-sm, 20px);
  text-decoration: none;
  color: var(--marbl-white-70, rgba(255, 255, 255, 0.7));
  border-radius: var(--radius-sm, 4px);
  transition: background 0.15s ease;
}
.kh-search-results__item + .kh-search-results__item { margin-top: var(--gap-3xs, 4px); }
.kh-search-results__item:hover,
.kh-search-results__item:focus-visible {
  background: var(--marbl-white-06, rgba(255, 255, 255, 0.06));
  color: var(--marbl-white, #ffffff);
  outline: none;
}

.kh-search-results__crumb {
  display: block;
  font-size: var(--text-xs, 11px);
  font-weight: var(--font-semibold, 600);
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--marbl-ember, #F35226);
  margin-bottom: var(--gap-3xs, 4px);
}
.kh-search-results__title {
  display: block;
  font-family: var(--font-heading, 'Urbanist', sans-serif);
  font-size: var(--text-base, 15px);
  font-weight: var(--font-semibold, 600);
  color: var(--marbl-white, #ffffff);
  margin-bottom: var(--gap-3xs, 4px);
}
.kh-search-results__snippet {
  display: block;
  font-size: var(--text-sm, 13px);
  line-height: 1.5;
  color: var(--marbl-white-50, rgba(255, 255, 255, 0.5));
}
.kh-search-results__empty {
  margin: 0;
  padding: var(--gap-xs, 10px) var(--gap-sm, 20px);
  font-size: var(--text-sm, 13px);
  color: var(--marbl-white-50, rgba(255, 255, 255, 0.5));
}
.kh-search-results mark {
  background: transparent;
  color: var(--marbl-ember, #F35226);
  font-weight: var(--font-semibold, 600);
}

/* Tree nav: ul/li, indent on nesting, no bullets */
.kh-nav { list-style: none; padding: 0; margin: 0; }
/* Obsidian-style: top-level groups stack tight, just enough breathing room. */
.kh-nav__group + .kh-nav__group { margin-top: var(--gap-3xs, 4px); }

/* Group label is a button — clicking expands/collapses the children
   with a slide animation. Chevron sits LEFT of the label (Obsidian-style).
   Sentence case (no uppercase / letter-spacing) so labels read like links. */
.kh-nav__group-label {
  display: flex;
  align-items: center;
  justify-content: flex-start;
  gap: var(--gap-2xs, 6px);
  width: 100%;
  padding: 0;
  background: transparent;
  border: 0;
  font-family: inherit;
  font-size: var(--text-sm, 13px);
  font-weight: var(--font-semibold, 600);
  letter-spacing: 0;
  text-transform: none;
  color: var(--marbl-white, #ffffff);
  margin: 0 0 var(--gap-3xs, 4px) 0;
  cursor: pointer;
  text-align: left;
  line-height: 1.5;
}

.kh-nav__group-label:focus-visible {
  outline: 2px solid var(--marbl-ember, #F35226);
  outline-offset: 2px;
  border-radius: var(--radius-xs, 2px);
}

/* Obsidian-style chevron: small, white, sits left of label.
   Default (expanded) = points down. Collapsed = points right. */
.kh-nav__group-chevron {
  width: 10px;
  height: 10px;
  flex-shrink: 0;
  transition: transform 0.2s ease;
  fill: none;
  stroke: var(--marbl-white, #ffffff);
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.kh-nav__group[aria-expanded="false"] > .kh-nav__group-label > .kh-nav__group-chevron {
  transform: rotate(-90deg);
}

/* Sliding-tier children container — collapses to height 0 when group is closed.
   Uses grid 1fr/0fr trick for true height animation without max-height guesswork.
   Wrapper is a div (not ul) so the inner ul can hold li children validly.
   Direct-child selectors so nested groups don't fight their parents. */
.kh-nav__children {
  display: grid;
  grid-template-rows: 1fr;
  transition: grid-template-rows 0.25s ease;
}

.kh-nav__children-inner {
  list-style: none;
  padding: 0;
  margin: 0;
  overflow: hidden;
  min-height: 0;
}

.kh-nav__group[aria-expanded="false"] > .kh-nav__children {
  grid-template-rows: 0fr;
}

/* Nested groups — indent by tier so the hierarchy reads visually. */
.kh-nav__children-inner .kh-nav__group {
  margin-top: var(--gap-xs, 10px);
  padding-left: var(--gap-xs, 10px);
}
.kh-nav__children-inner .kh-nav__children-inner .kh-nav__group {
  padding-left: var(--gap-sm, 20px);
}

.kh-nav__item { padding: var(--gap-3xs) 0; list-style: none; }
.kh-nav__item--nested { padding-left: var(--gap-sm, 20px); }

.kh-nav__link {
  display: block;
  color: var(--marbl-white-50, rgba(255, 255, 255, 0.5));
  text-decoration: none;
  line-height: 1.5;
  border-left: 2px solid transparent;
  padding-left: var(--gap-xs, 10px);
  margin-left: -10px;
  transition: color 0.15s ease, border-color 0.15s ease;
}

.kh-nav__link:hover {
  color: var(--marbl-white, #ffffff);
}

/* Active page: white text + subtle white border, NOT ember.
   Keeps the orange contained to group labels (intentional accent). */
.kh-nav__link[aria-current="page"] {
  color: var(--marbl-white, #ffffff);
  border-left-color: var(--marbl-white-30, rgba(255, 255, 255, 0.3));
  font-weight: var(--font-semibold, 600);
}

/* Top-level hierarchy emphasis (locked 29 Apr 2026):
   - direct .kh-nav children (top-level leaves + group labels) read WHITE
     and hover EMBER -- they're the entry points
   - nested children (everything inside .kh-nav__children-inner) keep the
     muted grey + white-on-hover treatment defined above */
.kh-nav > .kh-nav__item > .kh-nav__link {
  color: var(--marbl-white, #ffffff);
}
.kh-nav > .kh-nav__item > .kh-nav__link:hover {
  color: var(--marbl-ember, #F35226);
}
.kh-nav > .kh-nav__group > .kh-nav__group-label {
  color: var(--marbl-white, #ffffff);
}
.kh-nav > .kh-nav__group > .kh-nav__group-label:hover {
  color: var(--marbl-ember, #F35226);
}

/* Search filter: hide non-matching items + groups with no visible matches */
.kh-nav__item.is-hidden { display: none; }
.kh-nav__group.is-hidden { display: none; }

/* Sidebar top row: home icon button + search input on a single row.
   Pulls the Contents nav up the sidebar - the Search heading was
   removed because the input's placeholder + aria-label carry the
   meaning, and the heading was just adding vertical noise.
   Locked 30 Apr 2026. */
.kh-sidebar__top {
  display: flex;
  align-items: center;
  gap: var(--gap-xs, 10px);
  margin-bottom: var(--gap-sm, 20px);
}

.kh-sidebar__top .kh-sidebar__home {
  flex: 0 0 auto;
  margin: 0;
  text-decoration: none;
}

.kh-sidebar__top .kh-sidebar__search-field {
  flex: 1 1 auto;
  min-width: 0;
  margin: 0;                  /* override the standalone search-field's bottom margin */
}

.kh-sidebar__top .kh-sidebar__search {
  height: 40px;               /* match btn-icon--mini (home button is 40x40) */
  padding: 0;
  margin: 0;
  box-sizing: border-box;
  line-height: 38px;          /* 40 - 1 (border-bottom) - 1 (visual) */
}

/* === Article column (centre) === */

.kh-article {
  min-width: 0;
  max-width: var(--kh-article-max, 800px);
  margin: 0 auto;
  font-family: var(--font-body, 'Inter', sans-serif);
  color: var(--marbl-white-70, rgba(255, 255, 255, 0.7));
  line-height: 1.7;
}

/* Article header gap → 40 (was 80). Locked 30 Apr 2026 — section
   spacing is too loud at 80px between header and first content; 40
   reads as "next thing related" rather than "next section". */
.kh-article__header { margin-bottom: var(--gap-md, 40px); }

/* Featured image at top of an article. Sits above the eyebrow.
   Same border-radius as code blocks; full-bleed within the article column. */
.kh-article__featured {
  display: block;
  width: 100%;
  height: auto;
  margin: 0 0 var(--gap-md, 40px) 0;
  border-radius: var(--radius, 10px);
  border: 1px solid var(--marbl-white-08, rgba(255, 255, 255, 0.08));
}

/* Responsive YouTube / video embed wrapper.
   Use: <div class="kh-video"><iframe src="..." allowfullscreen></iframe></div> */
.kh-video {
  width: 100%;
  margin: var(--gap-md, 40px) 0;
  border-radius: var(--radius, 10px);
  overflow: hidden;
  border: 1px solid var(--marbl-white-08, rgba(255, 255, 255, 0.08));
  aspect-ratio: 16 / 9;
}
.kh-video iframe {
  width: 100%;
  height: 100%;
  border: 0;
  display: block;
}

.kh-article__eyebrow {
  font-size: var(--text-xs, 11px);
  font-weight: var(--font-semibold, 600);
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--marbl-ember, #F35226);
  margin: 0 0 var(--gap-sm, 20px) 0;
}

.kh-article__title {
  font-family: var(--font-heading, 'Urbanist', sans-serif);
  font-size: clamp(36px, 1.5rem + 2.5vw, 56px);
  font-weight: var(--font-bold, 700);
  line-height: 1.1;
  color: var(--marbl-white, #ffffff);
  letter-spacing: -0.02em;
  margin: 0 0 var(--gap-sm, 20px) 0;
  text-wrap: balance;
}

.kh-article__lead {
  font-size: var(--text-lg, 18px);
  line-height: 1.6;
  color: var(--marbl-white-70, rgba(255, 255, 255, 0.7));
  margin: 0;
  text-wrap: pretty;
}

.kh-article__body { font-size: var(--text-base, 15px); }

.kh-article__body h2 {
  font-family: var(--font-heading, 'Urbanist', sans-serif);
  font-size: clamp(24px, 1.2rem + 1vw, 32px);
  font-weight: var(--font-bold, 700);
  line-height: 1.2;
  color: var(--marbl-white, #ffffff);
  margin: var(--gap-xl, 80px) 0 var(--gap-sm, 20px) 0;
  padding-bottom: var(--gap-xs, 10px);
  border-bottom: 1px solid var(--marbl-white-08, rgba(255, 255, 255, 0.08));
  text-wrap: balance;
  scroll-margin-top: var(--gap-md, 40px);
}

/* Inline audio block at top of article body (KH §6.2). 40px gap below
   so the next h2 lands at consistent rhythm. Locked canonical 30 Apr
   2026 (was TAT-local in kh-content.css). */
.kh-article__body > .marbl-waveform.mwp-custom:first-child {
  margin: 0 0 var(--gap-md, 40px);
}

/* Strip trailing margin off the last paragraph in any article column or
   sub-section so the visual rhythm stays uniform between blocks. */
.kh-article__body p:last-of-type,
.kh-article__body article p:last-of-type {
  margin-bottom: 0;
}

.kh-article__body h3 {
  font-family: var(--font-heading, 'Urbanist', sans-serif);
  font-size: var(--text-xl, 20px);
  font-weight: var(--font-semibold, 600);
  color: var(--marbl-white, #ffffff);
  margin: var(--gap-md, 40px) 0 var(--gap-sm, 20px) 0;
  scroll-margin-top: var(--gap-md, 40px);
}

.kh-article__body p {
  margin: 0 0 var(--gap-sm, 20px) 0;
  text-wrap: pretty;
}

.kh-article__body ul,
.kh-article__body ol {
  margin: 0 0 var(--gap-sm, 20px) 0;
  padding-left: var(--gap-sm, 20px);
}

.kh-article__body li { margin: 0 0 var(--gap-tight) 0; }

/* Markdown horizontal rule — `---` in source. Visually collapsed to
   zero footprint: the surrounding h2 (80px top margin) creates the
   section break already, and a bare line in mid-article reads as
   random noise. Source semantics preserved — screen readers still
   announce the separator. Locked 30 Apr 2026. */
.kh-article__body hr {
  border: 0;
  height: 0;
  margin: 0;
}

.kh-article__body a {
  color: var(--marbl-ember, #F35226);
  text-decoration: none;
  border-bottom: 1px solid var(--marbl-ember-30, rgba(243, 82, 38, 0.3));
  transition: border-color 0.15s ease;
}
.kh-article__body a:hover { border-bottom-color: var(--marbl-ember, #F35226); }

.kh-article__body strong { color: var(--marbl-white, #ffffff); font-weight: var(--font-semibold, 600); }

.kh-article__body code {
  font-family: ui-monospace, 'SF Mono', Menlo, Monaco, Consolas, monospace;
  font-size: 0.9em;
  padding: 2px 6px;
  background: var(--marbl-white-06, rgba(255, 255, 255, 0.06));
  border-radius: var(--radius-sm, 4px);
  color: var(--marbl-white, #ffffff);
}

.kh-article__body pre {
  margin: var(--gap-sm, 20px) 0;
  padding: var(--gap-sm, 20px);
  background: var(--marbl-charcoal-light, #1d1a1b);
  border: 1px solid var(--marbl-white-06, rgba(255, 255, 255, 0.06));
  border-radius: var(--radius, 10px);
  overflow-x: auto;
  font-family: ui-monospace, 'SF Mono', Menlo, Monaco, Consolas, monospace;
  font-size: var(--text-sm, 13px);
  line-height: 1.6;
}
.kh-article__body pre code { padding: 0; background: transparent; border-radius: 0; }

.kh-article__body blockquote {
  margin: var(--gap-md, 40px) 0;
  padding: var(--gap-sm, 20px) var(--gap-md, 40px);
  border-left: 2px solid var(--marbl-ember, #F35226);
  color: var(--marbl-white-70, rgba(255, 255, 255, 0.7));
  font-style: italic;
  font-family: 'Petrona', Georgia, serif;
  font-size: var(--text-lg, 18px);
}

.kh-article__body hr {
  border: 0;
  height: 1px;
  background: var(--marbl-white-08, rgba(255, 255, 255, 0.08));
  margin: var(--gap-xl, 80px) 0;
}

/* Pagination at end of article */
.kh-pagination {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--gap-sm, 20px);
  margin-top: var(--gap-xl, 80px);
  padding-top: var(--gap-md, 40px);
  border-top: 1px solid var(--marbl-white-08, rgba(255, 255, 255, 0.08));
}

.kh-pagination__link {
  padding: var(--gap-sm, 20px);
  background: transparent;
  border: 1px solid var(--marbl-white-08, rgba(255, 255, 255, 0.08));
  border-radius: var(--radius, 10px);
  text-decoration: none;
  color: inherit;
  transition: border-color 0.15s ease;
}
.kh-pagination__link:hover { border-color: var(--marbl-white-15, rgba(255, 255, 255, 0.15)); }
.kh-pagination__link--prev { text-align: left; }
.kh-pagination__link--next { text-align: right; }

.kh-pagination__label {
  display: block;
  font-size: var(--text-xs, 11px);
  font-weight: var(--font-semibold, 600);
  letter-spacing: 2px;
  text-transform: uppercase;
  /* white-65 hits WCAG AA contrast ratio against --marbl-charcoal.
     white-40 was 3.5:1 (failed Lighthouse a11y). Locked 1 May 2026. */
  color: var(--marbl-white-65, rgba(255, 255, 255, 0.65));
  margin-bottom: var(--gap-tight);
}

.kh-pagination__title {
  font-family: var(--font-heading, 'Urbanist', sans-serif);
  font-size: var(--text-base, 15px);
  font-weight: var(--font-semibold, 600);
  color: var(--marbl-white, #ffffff);
}

/* === TOC (right) — sticky on this page === */

.kh-toc {
  position: sticky;
  top: var(--gap-md, 40px);
  max-height: calc(100dvh - var(--gap-md, 40px) * 2);
  overflow-y: auto;
  /* Full-card treatment: border on all sides, no background fill,
     standard radius + padding. Locked 30 Apr 2026 (replaced earlier
     border-left only). */
  border: 1px solid var(--marbl-white-08, rgba(255, 255, 255, 0.08));
  border-radius: var(--radius, 10px);
  padding: var(--gap-sm, 20px);
  font-family: var(--font-body, 'Inter', sans-serif);
  font-size: var(--text-xs, 11px);
}

/* Knowledge graph slot — sits above the "On this page" label inside
   the right column. Component to be plugged in (Obsidian-style force
   graph showing page relationships). Empty stub for now; the slot
   exists so consumers can drop in markup without re-shaping the
   canonical partial. Locked 30 Apr 2026. */
.kh-toc__graph {
  width: 100%;
  aspect-ratio: 1 / 1;
  margin-bottom: var(--gap-sm, 20px);
  border-bottom: 1px solid var(--marbl-white-08, rgba(255, 255, 255, 0.08));
  padding-bottom: var(--gap-sm, 20px);
}
.kh-toc__graph:empty { display: none; }

.kh-toc__label {
  font-size: var(--text-xs, 11px);
  font-weight: var(--font-semibold, 600);
  letter-spacing: 2px;
  text-transform: uppercase;
  color: var(--marbl-ember, #F35226);
  margin: 0 0 var(--gap-sm, 20px) 0;
}

.kh-toc__list { list-style: none; padding: 0; margin: 0; }
.kh-toc__item { padding: var(--gap-3xs) 0; }
.kh-toc__item--nested { padding-left: var(--gap-xs, 10px); }

.kh-toc__link {
  display: block;
  color: var(--marbl-white-50, rgba(255, 255, 255, 0.5));
  text-decoration: none;
  font-size: var(--text-sm, 13px);
  line-height: 1.5;
  transition: color 0.15s ease;
}
.kh-toc__link:hover { color: var(--marbl-white, #ffffff); }

/* Active TOC link: white not orange (contains ember to the section labels). */
.kh-toc__link[aria-current="true"] {
  color: var(--marbl-white, #ffffff);
  font-weight: var(--font-semibold, 600);
}

/* === Mobile-friendly drawer behaviour ===
   Below 1024px: drop right-side TOC. Below 768px: collapse left sidebar
   into a drawer (toggled by a button at the top of .kh-article). */

@media (max-width: 1024px) {
  .kh-shell {
    grid-template-columns: minmax(0, var(--kh-sidebar-w, 240px)) minmax(0, 1fr);
  }
  .kh-toc { display: none; }
}

/* Mobile drawer toggle: hidden on desktop. Below 768px it appears and the
   sidebar contents collapse beneath it (own grid-rows slide animation).
   Sized to match an input field (44px tap target, base text). */
.kh-sidebar__toggle {
  display: none;
  align-items: center;
  justify-content: space-between;
  width: 100%;
  min-height: 44px;
  padding: var(--gap-xs, 10px) var(--gap-sm, 20px);
  background: transparent;
  border: 1px solid var(--marbl-white-15, rgba(255, 255, 255, 0.15));
  border-radius: var(--radius, 10px);
  color: var(--marbl-white, #ffffff);
  font-family: inherit;
  font-size: var(--text-base, 15px);
  font-weight: var(--font-semibold, 600);
  cursor: pointer;
}

.kh-sidebar__toggle-chevron {
  width: 14px;
  height: 14px;
  flex-shrink: 0;
  transition: transform 0.25s ease;
  fill: none;
  stroke: currentColor;
  stroke-width: 2;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.kh-sidebar[aria-expanded="false"] .kh-sidebar__toggle-chevron {
  transform: rotate(-90deg);
}

@media (max-width: 768px) {
  .kh-shell {
    grid-template-columns: 1fr;
    padding: var(--gap-sm, 20px);
    gap: var(--gap-sm, 20px);
  }
  .kh-sidebar {
    position: relative;
    top: 0;
    max-height: none;
    border-bottom: 1px solid var(--marbl-white-08, rgba(255, 255, 255, 0.08));
    padding-bottom: var(--gap-sm, 20px);
    margin-bottom: var(--gap-sm, 20px);
  }

  .kh-sidebar__toggle { display: flex; }

  /* Sidebar contents (search + nav) collapsed in a sliding panel */
  .kh-sidebar__panel {
    display: grid;
    grid-template-rows: 1fr;
    transition: grid-template-rows 0.3s ease, margin-top 0.3s ease;
    margin-top: var(--gap-sm, 20px);
  }
  .kh-sidebar__panel > div {
    overflow: hidden;
    min-height: 0;
  }
  .kh-sidebar[aria-expanded="false"] .kh-sidebar__panel {
    grid-template-rows: 0fr;
    margin-top: 0;
  }
}

@media (prefers-reduced-motion: reduce) {
  .kh-nav__link,
  .kh-toc__link,
  .kh-article__body a,
  .kh-pagination__link { transition: none; }
}