/* BabianSpark — Express-flavored docs site
 * Brand color: #F59E0B (spark amber)
 * Layout signatures (36_express):
 *   - Light gray header strip with single row: brand · search · text nav · icons
 *   - Hero: very large serif-leaning headline + small mono code panel on right
 *   - Yellow-tinted callout banner (the "Express@5.1.0 LTS" strip)
 *   - 4-column simple text-only feature list (no card chrome)
 *   - Article: minimal three-column with light TOC, text-link breadcrumb, no shadows
 *   - Code blocks: very flat, soft gray (#F2F2F2) tinted, no rounded corners on hero pre
 *   - Lots of whitespace, blue-violet links (#3344BB-ish), serif taste in headings
 */

:root {
  /* spark amber palette */
  --bs-amber: #F59E0B;
  --bs-amber-d: #D97706;
  --bs-amber-dd: #B45309;
  --bs-amber-tint: #FFF6E5;
  --bs-amber-tint-2: #FFE9B7;
  --bs-amber-line: #F8C572;

  /* surfaces */
  --bs-surface: #FFFFFF;
  --bs-surface-soft: #FAFAFA;
  --bs-surface-rule: #F5F4F1;
  --bs-head-bg: #F4F4F4;
  --bs-callout: #FFF8E2;
  --bs-callout-line: #F0D88A;
  --bs-code-bg: #F2F2F2;
  --bs-code-bg-2: #ECECEC;

  /* text */
  --bs-ink: #1F1F1F;
  --bs-ink-soft: #2F2F2F;
  --bs-ink-mid: #555555;
  --bs-ink-mut: #7A7A7A;
  --bs-ink-faint: #9C9C9C;

  /* lines */
  --bs-line: #E2E2E2;
  --bs-line-soft: #ECECEC;
  --bs-line-strong: #C8C8C8;

  /* link palette (Express uses cool dark blue links) */
  --bs-link: #2B4ABF;
  --bs-link-hover: #1A2D80;
  --bs-link-visited: #6E47A8;

  /* code accents */
  --bs-co-key: #B91C5C;
  --bs-co-str: #1F7A4D;
  --bs-co-fn: #1E4FB8;
  --bs-co-cm: #7A7A7A;
  --bs-co-op: #D97706;

  /* rhythm */
  --bs-radius-x: 0;
  --bs-radius: 4px;
  --bs-radius-2: 6px;

  --bs-shadow-1: 0 1px 0 rgba(0,0,0,0.04);
  --bs-shadow-2: 0 1px 3px rgba(0,0,0,0.06);

  /* type */
  --bs-font: -apple-system, BlinkMacSystemFont, "Segoe UI", "Helvetica Neue", "PingFang SC", "Hiragino Sans GB", "Noto Sans CJK SC", "Microsoft YaHei", Arial, sans-serif;
  --bs-serif: "Iowan Old Style", "Apple Garamond", "Baskerville", "Times New Roman", "Droid Serif", "Times", "Source Serif Pro", "PingFang SC", "Songti SC", "STSong", serif;
  --bs-mono: ui-monospace, "Cascadia Code", "Consolas", "SFMono-Regular", "Menlo", "Source Code Pro", monospace;

  /* layout */
  --bs-head-h: 56px;
  --bs-rail-w: 268px;
  --bs-toc-w: 220px;
  --bs-content-max: 800px;
  --bs-shell-max: 1280px;
  --bs-hero-max: 1180px;
}

[data-bs-theme="dark"] {
  --bs-surface: #161616;
  --bs-surface-soft: #1B1B1B;
  --bs-surface-rule: #232323;
  --bs-head-bg: #202020;
  --bs-callout: #2B2412;
  --bs-callout-line: #6F541F;
  --bs-code-bg: #1F1F1F;
  --bs-code-bg-2: #262626;

  --bs-ink: #ECECEC;
  --bs-ink-soft: #D6D6D6;
  --bs-ink-mid: #B7B7B7;
  --bs-ink-mut: #8E8E8E;
  --bs-ink-faint: #6F6F6F;

  --bs-line: #2C2C2C;
  --bs-line-soft: #232323;
  --bs-line-strong: #3A3A3A;

  --bs-link: #8FA8FF;
  --bs-link-hover: #B6C5FF;
  --bs-link-visited: #C9A6F3;

  --bs-amber-tint: rgba(245, 158, 11, 0.12);
  --bs-amber-tint-2: rgba(245, 158, 11, 0.22);
  --bs-amber-line: rgba(245, 158, 11, 0.45);
}

/* =========================================================
   Reset + base
   ========================================================= */
* { box-sizing: border-box; }
html { -webkit-text-size-adjust: 100%; }
html, body { margin: 0; padding: 0; }
body.bs-body {
  font-family: var(--bs-font);
  font-size: 16px;
  line-height: 1.65;
  color: var(--bs-ink);
  background: var(--bs-surface);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}
img, svg { max-width: 100%; vertical-align: middle; }
hr { border: 0; border-top: 1px solid var(--bs-line); margin: 28px 0; }
button { font-family: inherit; cursor: pointer; background: none; border: 0; color: inherit; }

a { color: var(--bs-link); text-decoration: underline; text-decoration-color: rgba(43,74,191,0.32); text-underline-offset: 2px; }
a:hover { color: var(--bs-link-hover); text-decoration-color: currentColor; }
a:visited { color: var(--bs-link-visited); }
[data-bs-theme="dark"] a { text-decoration-color: rgba(143,168,255,0.35); }

::selection { background: var(--bs-amber-tint-2); color: var(--bs-ink); }

/* =========================================================
   Header (express signature: light gray strip, single row)
   ========================================================= */
.bs-head {
  position: sticky; top: 0; z-index: 50;
  background: var(--bs-head-bg);
  border-bottom: 1px solid var(--bs-line);
}
.bs-head__row {
  display: flex; align-items: center; gap: 18px;
  height: var(--bs-head-h);
  max-width: var(--bs-shell-max);
  margin: 0 auto;
  padding: 0 28px;
}
.bs-brand {
  display: inline-flex; align-items: center; gap: 8px;
  text-decoration: none; color: var(--bs-ink);
  font-family: var(--bs-serif);
}
.bs-brand:hover { text-decoration: none; color: var(--bs-amber-d); }
.bs-brand__mark { display: inline-flex; }
.bs-brand__name {
  font-size: 22px; font-weight: 400;
  letter-spacing: -0.01em;
  font-style: italic;
}
.bs-head__search {
  display: inline-flex; align-items: center; gap: 8px;
  background: var(--bs-surface);
  border: 1px solid var(--bs-line);
  border-radius: 4px;
  padding: 6px 10px;
  width: 200px;
  max-width: 220px;
}
.bs-head__search-ic { color: var(--bs-ink-faint); display: inline-flex; }
.bs-head__search-in {
  border: 0; outline: 0; background: transparent;
  font-size: 13px; color: var(--bs-ink); width: 100%;
  font-family: inherit;
}
.bs-head__search-in::placeholder { color: var(--bs-ink-faint); }

.bs-head__nav {
  display: flex; align-items: center; gap: 22px;
  flex: 1 1 auto;
  margin-left: 6px;
}
.bs-head__lk {
  display: inline-flex; align-items: center;
  font-size: 14px; color: var(--bs-ink-soft);
  text-decoration: none; padding: 4px 0;
  border-bottom: 1.5px solid transparent;
}
.bs-head__lk:hover { color: var(--bs-amber-d); text-decoration: none; }
.bs-head__lk.is-here {
  color: var(--bs-amber-dd);
  border-bottom-color: var(--bs-amber);
}

.bs-head__tail {
  display: inline-flex; align-items: center; gap: 10px;
  margin-left: auto;
}
.bs-head__rail-btn { display: none; padding: 6px; color: var(--bs-ink-soft); }
.bs-head__theme {
  display: inline-flex; padding: 6px; color: var(--bs-ink-soft);
  border-radius: 4px;
}
.bs-head__theme:hover { color: var(--bs-amber-d); }
.bs-head__theme-d { display: none; }
[data-bs-theme="dark"] .bs-head__theme-l { display: none; }
[data-bs-theme="dark"] .bs-head__theme-d { display: inline-flex; }

.bs-head__lang {
  position: relative;
}
.bs-head__lang-btn {
  display: inline-flex; align-items: center; gap: 5px;
  font-size: 13px; color: var(--bs-ink-soft);
  padding: 6px 8px; border-radius: 4px;
}
.bs-head__lang-btn:hover { color: var(--bs-amber-d); background: var(--bs-surface); }
.bs-head__lang-menu {
  position: absolute; top: calc(100% + 6px); right: 0;
  list-style: none; padding: 6px 0; margin: 0;
  background: var(--bs-surface);
  border: 1px solid var(--bs-line);
  min-width: 160px;
  display: none;
  box-shadow: var(--bs-shadow-2);
}
.bs-head__lang.is-on .bs-head__lang-menu { display: block; }
.bs-head__lang-menu li { padding: 0; }
.bs-head__lang-menu a {
  display: block; padding: 8px 14px;
  font-size: 13px; color: var(--bs-ink-soft);
  text-decoration: none;
}
.bs-head__lang-menu a:hover { background: var(--bs-amber-tint); color: var(--bs-amber-dd); }
.bs-head__lang-menu a.is-current { color: var(--bs-amber-dd); font-weight: 600; }

/* =========================================================
   Shell (article + rail)
   ========================================================= */
.bs-shell {
  max-width: var(--bs-shell-max);
  margin: 0 auto;
  display: block;
}
.bs-shell--with-rail {
  display: grid;
  grid-template-columns: var(--bs-rail-w) 1fr;
  gap: 0;
  padding: 0 28px;
}

/* =========================================================
   Rail (left sidebar — flat, indented text tree)
   ========================================================= */
.bs-rail {
  position: sticky; top: var(--bs-head-h);
  height: calc(100vh - var(--bs-head-h));
  overflow-y: auto;
  padding: 28px 22px 40px 0;
  border-right: 1px solid var(--bs-line);
}
.bs-rail__filter { padding: 0 0 14px 0; }
.bs-rail__filter-in {
  width: 100%; padding: 7px 10px;
  font-size: 13px; color: var(--bs-ink);
  border: 1px solid var(--bs-line);
  background: var(--bs-surface);
  border-radius: 4px; outline: 0;
  font-family: inherit;
}
.bs-rail__filter-in:focus { border-color: var(--bs-amber-line); }
.bs-rail__filter-in::placeholder { color: var(--bs-ink-faint); }

.bs-rail__group { padding: 6px 0 12px 0; }
.bs-rail__head {
  font-size: 12px; font-weight: 700;
  color: var(--bs-ink); letter-spacing: 0.04em;
  text-transform: uppercase;
  padding: 6px 4px;
  display: flex; align-items: center; gap: 6px;
}
.bs-rail__head--toggle { cursor: pointer; user-select: none; }
.bs-rail__head--toggle:hover { color: var(--bs-amber-d); }
.bs-rail__chev { display: inline-flex; color: var(--bs-ink-mut); transition: transform 0.18s; }
.bs-rail__group.is-folded .bs-rail__chev { transform: rotate(-90deg); }
.bs-rail__group.is-folded .bs-rail__list--sub { display: none; }

.bs-rail__list { list-style: none; padding: 0; margin: 0; }
.bs-rail__list--sub { padding-left: 4px; border-left: 1px solid var(--bs-line-soft); margin-left: 8px; }
.bs-rail__list li { line-height: 1.45; }
.bs-rail__lk {
  display: block; padding: 5px 8px;
  font-size: 13.5px; color: var(--bs-ink-mid);
  text-decoration: none; border-radius: 3px;
  border-left: 2px solid transparent;
  margin-left: -2px;
}
.bs-rail__lk:hover { color: var(--bs-amber-d); background: var(--bs-amber-tint); text-decoration: none; }
.bs-rail__lk.is-here {
  color: var(--bs-amber-dd);
  background: var(--bs-amber-tint);
  border-left-color: var(--bs-amber);
  font-weight: 600;
}
.bs-rail__lk--cat { font-weight: 600; color: var(--bs-ink-soft); }

/* =========================================================
   Main column
   ========================================================= */
.bs-main {
  padding: 36px 0 64px 32px;
  min-width: 0;
}
.bs-main--wide {
  padding: 0 0 64px 0;
  max-width: 100%;
}

/* =========================================================
   Hero (express-style: huge serif headline + code panel)
   ========================================================= */
.bs-hero {
  background: var(--bs-surface);
  padding: 64px 28px 40px;
}
.bs-hero__inner {
  max-width: var(--bs-hero-max);
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(0, 1.05fr) minmax(0, 1fr);
  gap: 56px; align-items: start;
}
.bs-hero__lead {}
.bs-hero__h1 {
  font-family: var(--bs-serif);
  font-weight: 400;
  font-size: clamp(40px, 5.4vw, 68px);
  line-height: 1.05;
  letter-spacing: -0.015em;
  margin: 0 0 22px;
  color: var(--bs-ink);
}
.bs-hero__lede {
  font-family: var(--bs-serif);
  font-weight: 400;
  font-size: 22px;
  line-height: 1.45;
  color: var(--bs-ink-mid);
  margin: 0 0 28px;
  max-width: 540px;
}
.bs-hero__search {
  display: flex; align-items: center; gap: 10px;
  background: var(--bs-surface-soft);
  border: 1px solid var(--bs-line);
  padding: 10px 14px;
  max-width: 480px;
  margin-bottom: 22px;
}
.bs-hero__search-ic { color: var(--bs-ink-faint); display: inline-flex; }
.bs-hero__search-in {
  flex: 1; border: 0; outline: 0; background: transparent;
  font-size: 14px; color: var(--bs-ink);
  font-family: var(--bs-mono);
}
.bs-hero__search-in::placeholder { color: var(--bs-ink-faint); }
.bs-hero__btns { display: inline-flex; align-items: center; gap: 14px; flex-wrap: wrap; }

.bs-btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 10px 20px;
  font-size: 14px; font-weight: 500;
  text-decoration: none;
  border: 1px solid transparent;
  transition: background-color 0.15s, color 0.15s, border-color 0.15s;
  border-radius: 4px;
}
.bs-btn--solid {
  background: var(--bs-amber);
  color: #1F1F1F;
  border-color: var(--bs-amber);
}
.bs-btn--solid:hover { background: var(--bs-amber-d); border-color: var(--bs-amber-d); color: #FFF; text-decoration: none; }
.bs-btn--ghost {
  background: transparent;
  color: var(--bs-link);
  border-color: var(--bs-line);
}
.bs-btn--ghost:hover { background: var(--bs-surface-soft); border-color: var(--bs-link); text-decoration: none; }

/* mock terminal panel */
.bs-hero__panel {
  background: var(--bs-code-bg);
  border: 1px solid var(--bs-line);
  font-family: var(--bs-mono);
  font-size: 13.5px;
  margin-top: 4px;
}
.bs-hero__panel-bar {
  display: flex; align-items: center; gap: 8px;
  padding: 8px 14px;
  border-bottom: 1px solid var(--bs-line);
  background: var(--bs-code-bg-2);
  font-size: 11.5px; color: var(--bs-ink-mut);
}
.bs-hero__dot { width: 9px; height: 9px; border-radius: 50%; display: inline-block; }
.bs-hero__dot--r { background: #E55B5B; }
.bs-hero__dot--y { background: #E8B637; }
.bs-hero__dot--g { background: #59B954; }
.bs-hero__panel-name { margin-left: 10px; font-family: var(--bs-mono); font-size: 11.5px; }
.bs-hero__panel-pre {
  margin: 0; padding: 18px 18px 22px;
  white-space: pre;
  overflow-x: auto;
  color: var(--bs-ink-soft);
  line-height: 1.7;
}
.bs-hl-co { color: var(--bs-co-cm); font-style: italic; }
.bs-hl-kw { color: var(--bs-co-key); font-weight: 600; }
.bs-hl-st { color: var(--bs-co-str); }
.bs-hl-fn { color: var(--bs-co-fn); }
.bs-hl-op { color: var(--bs-co-op); font-weight: 600; }

/* =========================================================
   Banner (express LTS-style yellow callout)
   ========================================================= */
.bs-banner {
  background: var(--bs-callout);
  border-top: 1px solid var(--bs-callout-line);
  border-bottom: 1px solid var(--bs-callout-line);
  padding: 14px 28px;
}
.bs-banner__inner {
  max-width: var(--bs-hero-max);
  margin: 0 auto;
  display: flex; align-items: center; gap: 12px;
  flex-wrap: wrap;
  font-size: 14.5px; color: var(--bs-ink-soft);
}
.bs-banner__bullet { color: var(--bs-amber-d); display: inline-flex; }
.bs-banner__text { flex: 1; min-width: 200px; }
.bs-banner__link {
  font-size: 13.5px;
  text-decoration: underline; text-decoration-color: rgba(43,74,191,0.32);
}

/* =========================================================
   Cards row (express 4-column flat feature list)
   ========================================================= */
.bs-cards {
  padding: 56px 28px 32px;
  border-bottom: 1px solid var(--bs-line);
}
.bs-cards__inner {
  max-width: var(--bs-hero-max);
  margin: 0 auto;
}
.bs-cards__row {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 36px 36px;
  margin-bottom: 36px;
}
.bs-cards__row:last-child { margin-bottom: 0; }
.bs-cards__cell {
  display: block;
  padding: 0;
  text-decoration: none;
  color: var(--bs-ink);
  border: 0;
}
.bs-cards__cell:hover { text-decoration: none; }
.bs-cards__cell:hover .bs-cards__h { color: var(--bs-amber-d); }
.bs-cards__h {
  font-family: var(--bs-serif);
  font-weight: 400;
  font-size: 22px;
  line-height: 1.2;
  margin: 0 0 8px;
  color: var(--bs-ink);
  letter-spacing: -0.005em;
}
.bs-cards__d {
  font-size: 14.5px;
  line-height: 1.55;
  color: var(--bs-ink-mid);
  margin: 0;
}

/* =========================================================
   Content sections (more topics / latest / faq)
   ========================================================= */
.bs-section {
  padding: 56px 28px;
}
.bs-section--alt {
  background: var(--bs-surface-soft);
  border-top: 1px solid var(--bs-line);
  border-bottom: 1px solid var(--bs-line);
}
.bs-section__inner {
  max-width: var(--bs-hero-max);
  margin: 0 auto;
}
.bs-section__head { margin-bottom: 28px; }
.bs-section__h2 {
  font-family: var(--bs-serif);
  font-weight: 400;
  font-size: 32px;
  line-height: 1.2;
  letter-spacing: -0.01em;
  margin: 0 0 8px;
  color: var(--bs-ink);
}
.bs-section__sub {
  font-size: 15px; color: var(--bs-ink-mid);
  margin: 0; max-width: 720px;
}
.bs-section__more {
  margin-top: 18px;
  font-size: 14px;
}

/* reflist (more topics) */
.bs-reflist {
  list-style: none; padding: 0; margin: 0;
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 14px 36px;
}
.bs-reflist li {
  padding: 14px 0;
  border-bottom: 1px solid var(--bs-line-soft);
  display: flex; flex-direction: column; gap: 4px;
}
.bs-reflist li a { font-size: 16px; }
.bs-reflist__d {
  font-size: 13.5px; color: var(--bs-ink-mut);
}

/* postlist */
.bs-postlist { list-style: none; padding: 0; margin: 0; }
.bs-postlist__item {
  padding: 18px 0;
  border-bottom: 1px solid var(--bs-line-soft);
}
.bs-postlist__item:first-child { padding-top: 0; }
.bs-postlist__t {
  display: block;
  font-family: var(--bs-serif);
  font-size: 19px; font-weight: 400;
  color: var(--bs-ink);
  margin-bottom: 6px;
  text-decoration: none;
  letter-spacing: -0.005em;
  line-height: 1.4;
}
.bs-postlist__t:hover { color: var(--bs-amber-d); text-decoration: none; }
.bs-postlist__meta { display: flex; align-items: center; gap: 12px; flex-wrap: wrap; margin-bottom: 4px; }
.bs-postlist__dt { font-size: 12.5px; color: var(--bs-ink-mut); font-family: var(--bs-mono); }
.bs-postlist__chip {
  font-size: 11.5px;
  padding: 2px 8px;
  background: var(--bs-amber-tint);
  color: var(--bs-amber-dd);
  border-radius: 2px;
  text-transform: uppercase;
  letter-spacing: 0.03em;
}
.bs-postlist__d {
  font-size: 14px; color: var(--bs-ink-mid);
  margin: 4px 0 0; line-height: 1.55;
}

/* faq */
.bs-faq { display: flex; flex-direction: column; gap: 6px; }
.bs-faq__item {
  border-bottom: 1px solid var(--bs-line-soft);
  padding: 4px 0;
}
.bs-faq__q {
  cursor: pointer;
  font-size: 15.5px; font-weight: 600;
  color: var(--bs-ink-soft);
  padding: 12px 4px 12px 24px;
  position: relative;
  list-style: none;
}
.bs-faq__q::-webkit-details-marker { display: none; }
.bs-faq__q::before {
  content: '+';
  position: absolute; left: 4px; top: 11px;
  color: var(--bs-amber-d);
  font-family: var(--bs-mono);
  font-size: 18px;
  line-height: 1;
}
.bs-faq__item[open] .bs-faq__q::before { content: '–'; }
.bs-faq__a {
  padding: 0 4px 14px 24px;
  font-size: 14.5px; color: var(--bs-ink-mid); line-height: 1.7;
}
.bs-faq__a p { margin: 0; }

/* topic grid */
.bs-topic-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 18px 22px;
  margin-top: 18px;
}
.bs-topic-cell {
  display: block;
  padding: 18px 20px;
  text-decoration: none;
  background: var(--bs-surface);
  border: 1px solid var(--bs-line);
  border-radius: 4px;
  color: var(--bs-ink);
  transition: border-color 0.15s, background 0.15s;
}
.bs-topic-cell:hover {
  border-color: var(--bs-amber);
  background: var(--bs-amber-tint);
  text-decoration: none;
}
.bs-topic-cell__h {
  font-family: var(--bs-serif);
  font-size: 19px;
  margin-bottom: 6px;
  color: var(--bs-ink);
}
.bs-topic-cell__d {
  font-size: 13.5px;
  color: var(--bs-ink-mut);
  line-height: 1.5;
  margin: 0 0 10px;
}
.bs-topic-cell__count {
  font-size: 12px; color: var(--bs-amber-dd);
  font-family: var(--bs-mono);
  letter-spacing: 0.03em;
}

/* =========================================================
   Article (post / page)
   ========================================================= */
.bs-article {
  padding: 28px 0 40px;
}
.bs-article--page {
  max-width: var(--bs-content-max);
  margin: 0;
}
.bs-article--list { padding-top: 32px; }
.bs-article--doc { padding-top: 22px; }

.bs-crumb {
  font-size: 13px;
  color: var(--bs-ink-mut);
  margin-bottom: 18px;
  display: flex; flex-wrap: wrap; align-items: center; gap: 6px;
}
.bs-crumb a {
  color: var(--bs-link);
  text-decoration: none;
}
.bs-crumb a:hover { color: var(--bs-link-hover); text-decoration: underline; }
.bs-crumb__sep { color: var(--bs-ink-faint); user-select: none; }
.bs-crumb__here { color: var(--bs-ink-soft); }

.bs-article__head { margin-bottom: 26px; padding-bottom: 18px; border-bottom: 1px solid var(--bs-line-soft); }
.bs-article__h1 {
  font-family: var(--bs-serif);
  font-weight: 400;
  font-size: clamp(28px, 3.5vw, 40px);
  line-height: 1.18;
  letter-spacing: -0.01em;
  color: var(--bs-ink);
  margin: 0 0 12px;
}
.bs-article__sub {
  font-family: var(--bs-serif);
  font-size: 18px;
  color: var(--bs-ink-mid);
  margin: 0 0 14px;
  line-height: 1.45;
}
.bs-meta {
  display: flex; align-items: center; gap: 8px;
  font-size: 13px; color: var(--bs-ink-mut);
  flex-wrap: wrap;
}
.bs-meta__bit { font-family: var(--bs-mono); font-size: 12.5px; }
.bs-meta__dot { color: var(--bs-ink-faint); }
.bs-meta__chip {
  display: inline-block;
  padding: 2px 8px;
  background: var(--bs-amber-tint);
  color: var(--bs-amber-dd);
  font-size: 11.5px;
  text-decoration: none;
  border-radius: 2px;
}
.bs-meta__chip:hover { background: var(--bs-amber-tint-2); text-decoration: none; }

.bs-article__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) var(--bs-toc-w);
  gap: 36px;
  align-items: start;
}

/* =========================================================
   Prose (article body)
   ========================================================= */
.bs-prose {
  font-size: 16px;
  line-height: 1.78;
  color: var(--bs-ink-soft);
  max-width: var(--bs-content-max);
}
.bs-prose > :first-child { margin-top: 0; }
.bs-prose > :last-child { margin-bottom: 0; }

.bs-prose p { margin: 0 0 16px; }

.bs-prose h2 {
  font-family: var(--bs-serif);
  font-weight: 400;
  font-size: 28px;
  line-height: 1.25;
  margin: 40px 0 16px;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--bs-line-soft);
  color: var(--bs-ink);
  letter-spacing: -0.005em;
  scroll-margin-top: calc(var(--bs-head-h) + 12px);
}
.bs-prose h3 {
  font-family: var(--bs-serif);
  font-weight: 600;
  font-size: 21px;
  line-height: 1.3;
  margin: 28px 0 12px;
  color: var(--bs-ink);
  scroll-margin-top: calc(var(--bs-head-h) + 12px);
}
.bs-prose h4 {
  font-weight: 600; font-size: 17px;
  margin: 22px 0 8px;
  color: var(--bs-ink);
}

.bs-prose ul, .bs-prose ol {
  padding-left: 24px;
  margin: 0 0 16px;
}
.bs-prose li { margin: 4px 0; }

.bs-prose blockquote {
  margin: 18px 0;
  padding: 10px 16px 10px 18px;
  border-left: 3px solid var(--bs-amber);
  background: var(--bs-amber-tint);
  color: var(--bs-ink-soft);
  font-style: italic;
}
.bs-prose blockquote p:last-child { margin-bottom: 0; }

.bs-prose strong { color: var(--bs-ink); font-weight: 700; }

/* code */
.bs-prose code {
  font-family: var(--bs-mono);
  font-size: 0.92em;
  background: var(--bs-code-bg);
  padding: 2px 6px;
  border-radius: 3px;
  border: 1px solid var(--bs-line-soft);
  color: var(--bs-ink-soft);
}
.bs-prose pre {
  background: var(--bs-code-bg);
  border: 1px solid var(--bs-line);
  border-radius: 4px;
  padding: 14px 16px;
  overflow-x: auto;
  margin: 16px 0;
  line-height: 1.6;
  font-size: 13.5px;
}
.bs-prose pre code {
  background: transparent;
  border: 0;
  padding: 0;
  font-size: inherit;
}

/* tables */
.bs-prose table {
  width: 100%;
  border-collapse: collapse;
  margin: 18px 0;
  font-size: 14.5px;
}
.bs-prose th, .bs-prose td {
  border: 1px solid var(--bs-line);
  padding: 8px 12px;
  vertical-align: top;
  text-align: left;
}
.bs-prose th {
  background: var(--bs-surface-soft);
  font-weight: 600;
  color: var(--bs-ink);
}
.bs-prose tr:nth-child(2n) td { background: var(--bs-surface-soft); }

/* anchored headings */
.bs-prose h2 a.bs-anchor,
.bs-prose h3 a.bs-anchor { opacity: 0; margin-left: 6px; font-weight: 400; color: var(--bs-amber-d); text-decoration: none; }
.bs-prose h2:hover a.bs-anchor,
.bs-prose h3:hover a.bs-anchor { opacity: 1; }

/* =========================================================
   TOC (right rail)
   ========================================================= */
.bs-toc {
  position: sticky;
  top: calc(var(--bs-head-h) + 24px);
  align-self: start;
  font-size: 13px;
  max-height: calc(100vh - var(--bs-head-h) - 40px);
  overflow-y: auto;
  padding-left: 16px;
  border-left: 1px solid var(--bs-line-soft);
}
.bs-toc__inner { padding-bottom: 24px; }
.bs-toc__head {
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  color: var(--bs-ink-mut);
  margin-bottom: 10px;
}
.bs-toc__list { list-style: none; padding: 0; margin: 0 0 16px; }
.bs-toc__item { line-height: 1.5; margin: 4px 0; }
.bs-toc__item--lv3 { padding-left: 14px; }
.bs-toc__item a {
  display: block;
  padding: 3px 0;
  color: var(--bs-ink-mut);
  text-decoration: none;
  font-size: 12.8px;
  border-left: 2px solid transparent;
  margin-left: -10px;
  padding-left: 8px;
}
.bs-toc__item a:hover { color: var(--bs-amber-d); }
.bs-toc__item a.is-here {
  color: var(--bs-amber-dd);
  border-left-color: var(--bs-amber);
  font-weight: 600;
}
.bs-toc__list--plain .bs-toc__item { padding-left: 0; }
.bs-toc__more { padding-top: 10px; border-top: 1px solid var(--bs-line-soft); }

/* =========================================================
   Prev/Next (flip)
   ========================================================= */
.bs-flip {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 40px;
  padding-top: 24px;
  border-top: 1px solid var(--bs-line);
}
.bs-flip__cell {
  display: flex; flex-direction: column;
  padding: 14px 18px;
  border: 1px solid var(--bs-line);
  text-decoration: none;
  color: var(--bs-ink);
  background: var(--bs-surface);
  border-radius: 4px;
  transition: border-color 0.15s, background 0.15s;
}
.bs-flip__cell:hover {
  border-color: var(--bs-amber);
  background: var(--bs-amber-tint);
  text-decoration: none;
}
.bs-flip__cell:hover .bs-flip__t { color: var(--bs-amber-dd); }
.bs-flip__lab {
  display: inline-flex; align-items: center; gap: 6px;
  font-size: 12px; color: var(--bs-ink-mut);
  margin-bottom: 4px;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}
.bs-flip__t {
  font-family: var(--bs-serif);
  font-size: 16px;
  color: var(--bs-ink);
  line-height: 1.4;
}
.bs-flip__next { text-align: right; }
.bs-flip__next .bs-flip__lab { justify-content: flex-end; }

/* =========================================================
   Pager
   ========================================================= */
.bs-pager {
  display: flex; align-items: center; justify-content: center; gap: 6px;
  margin: 32px 0 16px;
  flex-wrap: wrap;
}
.bs-pager__btn,
.bs-pager__num {
  display: inline-flex; align-items: center; justify-content: center;
  min-width: 34px; height: 34px;
  padding: 0 10px;
  font-size: 13px;
  border: 1px solid var(--bs-line);
  background: var(--bs-surface);
  color: var(--bs-ink-soft);
  text-decoration: none;
  border-radius: 4px;
  font-family: var(--bs-mono);
}
.bs-pager__btn:hover,
.bs-pager__num:hover {
  border-color: var(--bs-amber);
  color: var(--bs-amber-dd);
  background: var(--bs-amber-tint);
  text-decoration: none;
}
.bs-pager__num.is-here {
  background: var(--bs-amber);
  border-color: var(--bs-amber);
  color: #1F1F1F;
  font-weight: 600;
}
.bs-pager__btn.is-off,
.bs-pager__num.is-off {
  opacity: 0.45;
  pointer-events: none;
}

/* =========================================================
   404
   ========================================================= */
.bs-404 {
  max-width: 620px;
  margin: 80px auto;
  padding: 0 28px;
  text-align: center;
}
.bs-404__code {
  font-family: var(--bs-serif);
  font-size: 96px;
  line-height: 1;
  color: var(--bs-amber);
  margin-bottom: 14px;
  letter-spacing: -0.02em;
}
.bs-404__h {
  font-family: var(--bs-serif);
  font-weight: 400;
  font-size: 28px;
  margin: 0 0 14px;
  color: var(--bs-ink);
}
.bs-404__d {
  font-size: 15px;
  color: var(--bs-ink-mid);
  margin: 0 0 26px;
}

/* =========================================================
   Footer (express simple gray footer)
   ========================================================= */
.bs-foot {
  margin-top: 48px;
  background: var(--bs-surface-soft);
  border-top: 1px solid var(--bs-line);
  color: var(--bs-ink-soft);
  font-size: 13px;
}
.bs-foot__top {
  max-width: var(--bs-shell-max);
  margin: 0 auto;
  padding: 36px 28px 24px;
  display: grid;
  grid-template-columns: minmax(220px, 1fr) minmax(0, 2.5fr);
  gap: 36px;
}
.bs-foot__brand {}
.bs-foot__logo {
  display: inline-flex; align-items: center; gap: 8px;
  text-decoration: none;
  color: var(--bs-ink);
  font-family: var(--bs-serif);
  margin-bottom: 8px;
}
.bs-foot__logo:hover { color: var(--bs-amber-d); text-decoration: none; }
.bs-foot__logo-name { font-size: 18px; font-style: italic; }
.bs-foot__pitch {
  font-size: 13px; color: var(--bs-ink-mut);
  margin: 6px 0 0; line-height: 1.6;
  max-width: 320px;
}
.bs-foot__cols {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 24px;
}
.bs-foot__col ul { list-style: none; padding: 0; margin: 0; }
.bs-foot__col li { margin: 5px 0; }
.bs-foot__col a {
  font-size: 13px;
  color: var(--bs-ink-mid);
  text-decoration: none;
}
.bs-foot__col a:hover { color: var(--bs-amber-d); text-decoration: underline; }
.bs-foot__col a.is-current { color: var(--bs-amber-dd); font-weight: 600; }
.bs-foot__h {
  font-size: 12px; font-weight: 700;
  color: var(--bs-ink); letter-spacing: 0.06em;
  text-transform: uppercase;
  margin-bottom: 12px;
}
.bs-foot__lang { display: flex; flex-wrap: wrap; gap: 8px 12px; }
.bs-foot__lang li { margin: 0; }

.bs-foot__bar {
  border-top: 1px solid var(--bs-line);
  padding: 18px 28px;
  max-width: var(--bs-shell-max);
  margin: 0 auto;
  display: flex; justify-content: space-between; align-items: flex-start;
  gap: 24px; flex-wrap: wrap;
  font-size: 12.5px; color: var(--bs-ink-mut);
}
.bs-foot__rights { font-family: var(--bs-mono); font-size: 12px; }
.bs-foot__risk { max-width: 720px; line-height: 1.6; }

/* =========================================================
   Responsive
   ========================================================= */
@media (max-width: 1080px) {
  .bs-hero__inner {
    grid-template-columns: 1fr;
    gap: 40px;
  }
  .bs-cards__row { grid-template-columns: repeat(2, 1fr); gap: 28px 32px; }
  .bs-foot__top { grid-template-columns: 1fr; }
  .bs-foot__cols { grid-template-columns: repeat(2, 1fr); }
  .bs-topic-grid { grid-template-columns: repeat(2, 1fr); }
  .bs-reflist { grid-template-columns: 1fr; }
}

@media (max-width: 880px) {
  :root {
    --bs-head-h: 52px;
  }
  .bs-head__row { padding: 0 18px; gap: 12px; }
  .bs-head__nav { display: none; }
  .bs-head__search { width: 140px; }
  .bs-head__rail-btn { display: inline-flex; }

  .bs-shell--with-rail {
    grid-template-columns: 1fr;
    padding: 0 18px;
  }
  .bs-rail {
    position: fixed;
    top: var(--bs-head-h);
    left: 0;
    width: 86%; max-width: 320px;
    height: calc(100vh - var(--bs-head-h));
    background: var(--bs-surface);
    border-right: 1px solid var(--bs-line);
    padding: 18px 18px 32px;
    z-index: 60;
    transform: translateX(-105%);
    transition: transform 0.22s ease;
    box-shadow: var(--bs-shadow-2);
  }
  .bs-rail.is-open { transform: translateX(0); }
  body.bs-rail-open { overflow: hidden; }

  .bs-main { padding: 24px 0 48px; }

  .bs-hero { padding: 40px 18px 28px; }
  .bs-hero__h1 { font-size: 38px; }
  .bs-hero__lede { font-size: 18px; }
  .bs-hero__panel-pre { font-size: 12.5px; }

  .bs-cards { padding: 36px 18px 24px; }
  .bs-cards__row { gap: 24px 22px; margin-bottom: 24px; }
  .bs-cards__h { font-size: 19px; }

  .bs-section { padding: 36px 18px; }
  .bs-section__h2 { font-size: 26px; }

  .bs-banner { padding: 12px 18px; }
  .bs-banner__inner { font-size: 13.5px; }

  .bs-article__row { grid-template-columns: 1fr; }
  .bs-toc { display: none; }

  .bs-flip { grid-template-columns: 1fr; }
  .bs-flip__next { text-align: left; }
  .bs-flip__next .bs-flip__lab { justify-content: flex-start; }

  .bs-foot__top { padding: 28px 18px 18px; gap: 24px; }
  .bs-foot__cols { grid-template-columns: 1fr 1fr; gap: 18px; }
  .bs-foot__bar { padding: 14px 18px; }

  .bs-topic-grid { grid-template-columns: 1fr; }
}

@media (max-width: 540px) {
  .bs-cards__row { grid-template-columns: 1fr; gap: 18px; margin-bottom: 18px; }
  .bs-hero__h1 { font-size: 32px; }
  .bs-hero__lede { font-size: 16px; }
  .bs-section__h2 { font-size: 22px; }
  .bs-article__h1 { font-size: 26px; }
  .bs-article__sub { font-size: 16px; }
  .bs-prose { font-size: 15.5px; }
  .bs-prose h2 { font-size: 23px; }
  .bs-prose h3 { font-size: 18px; }
  .bs-foot__cols { grid-template-columns: 1fr; }
}

/* =========================================================
   Print
   ========================================================= */
@media print {
  .bs-head, .bs-rail, .bs-toc, .bs-flip, .bs-foot, .bs-pager, .bs-banner { display: none !important; }
  .bs-shell--with-rail { display: block; padding: 0; }
  .bs-main { padding: 0; }
  .bs-prose { max-width: none; font-size: 12pt; line-height: 1.55; }
  .bs-prose pre { white-space: pre-wrap; }
  body { background: #fff; color: #000; }
  a { color: #000; text-decoration: underline; }
}

/* =========================================================
   Misc
   ========================================================= */
.bs-mobile-only { display: none; }
@media (max-width: 880px) { .bs-mobile-only { display: inline-flex; } }

/* details disclosure on dark theme */
[data-bs-theme="dark"] .bs-faq__q { color: var(--bs-ink); }
[data-bs-theme="dark"] .bs-prose pre { background: var(--bs-code-bg); border-color: var(--bs-line); }
[data-bs-theme="dark"] .bs-hero__panel { background: #1A1A1A; border-color: var(--bs-line); }
[data-bs-theme="dark"] .bs-hero__panel-bar { background: #222; border-color: var(--bs-line); }
[data-bs-theme="dark"] .bs-postlist__chip { background: var(--bs-amber-tint); color: var(--bs-amber); }
[data-bs-theme="dark"] .bs-meta__chip { background: var(--bs-amber-tint); color: var(--bs-amber); }
[data-bs-theme="dark"] .bs-prose tr:nth-child(2n) td { background: var(--bs-surface-rule); }

/* link underline in hero */
.bs-hero__lede a { color: var(--bs-link); text-decoration: underline; }

/* sticky offset for in-page anchor jumps */
:target { scroll-margin-top: calc(var(--bs-head-h) + 12px); }

/* End of style.css */