*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --bg: #ffffff;
  --sidebar: #f9fafb;
  --text: #111827;
  --text-2: #374151;
  --muted: #6b7280;
  --border: #e5e7eb;
  --accent: #111827;
}

/* Dark theme */
html.dark,
[data-theme="dark"] {
  --bg: #0f1117;
  --sidebar: #1a1d27;
  --text: #f3f4f6;
  --text-2: #d1d5db;
  --muted: #9ca3af;
  --border: #2d3148;
  --accent: #f3f4f6;
}

html.dark .topbar,
[data-theme="dark"] .topbar {
  background: rgba(15, 17, 23, .9);
}

html {
  scroll-behavior: smooth;
}

body {
  font-family: Inter, "Segoe UI", system-ui, sans-serif;
  font-size: 15px;
  line-height: 1.75;
  background: var(--bg);
  color: var(--text);
  -webkit-font-smoothing: antialiased;
}

/* ── Topbar ── */
.topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  height: 56px;
  display: flex;
  align-items: center;
  padding: 0 32px;
  background: rgba(255, 255, 255, .9);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border);
}

.topbar-inner {
  width: 100%;
  max-width: 1100px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.topbar-brand {
  font-size: 15px;
  font-weight: 700;
  color: var(--text);
  text-decoration: none;
  letter-spacing: -.3px;
}

.topbar-back {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  font-size: 13.5px;
  font-weight: 500;
  color: var(--muted);
  text-decoration: none;
  transition: color .15s;
}

.topbar-back:hover {
  color: var(--text);
}

.topbar-controls {
  display: flex;
  align-items: center;
  gap: 14px;
}

.topbar-lang {
  font: inherit;
  font-size: 13px;
  font-weight: 600;
  color: var(--muted);
  background: none;
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 4px 9px;
  cursor: pointer;
  transition: color .15s, border-color .15s;
}

.topbar-lang:hover {
  color: var(--text);
  border-color: var(--muted);
}

.doc-disclaimer {
  font-size: 13px;
  color: var(--muted);
  font-style: italic;
  margin-top: 10px;
}

.doc-disclaimer:empty {
  display: none;
}

/* ── Layout ── */
.layout {
  max-width: 1100px;
  margin: 0 auto;
  padding: 48px 32px 96px;
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 48px;
  align-items: start;
}

/* ── Sidebar TOC ── */
.toc {
  position: sticky;
  top: 72px;
  background: var(--sidebar);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 20px;
}

.toc-title {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: .8px;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 12px;
}

.toc-title--section {
  margin-top: 20px;
  padding-top: 16px;
  border-top: 1px solid var(--border);
}

.toc-list,
.doc-list {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.toc-list a,
.doc-list a {
  display: block;
  font-size: 13px;
  font-weight: 500;
  color: var(--muted);
  text-decoration: none;
  padding: 5px 8px;
  border-radius: 6px;
  transition: background .12s, color .12s;
  line-height: 1.4;
}

.toc-list a:hover,
.doc-list a:hover {
  background: var(--border);
  color: var(--text);
}

.toc-list a.active,
.doc-list a.active {
  background: var(--border);
  color: var(--text);
}

/* ── Content ── */
.content {
  min-width: 0;
}

.doc-header {
  margin-bottom: 48px;
  padding-bottom: 32px;
  border-bottom: 1px solid var(--border);
}

.doc-tag {
  display: inline-block;
  font-size: 11.5px;
  font-weight: 600;
  letter-spacing: .4px;
  text-transform: uppercase;
  color: var(--muted);
  background: var(--sidebar);
  border: 1px solid var(--border);
  padding: 3px 10px;
  border-radius: 6px;
  margin-bottom: 16px;
}

.doc-title {
  font-size: clamp(22px, 3vw, 30px);
  font-weight: 800;
  letter-spacing: -.8px;
  color: var(--text);
  line-height: 1.2;
  margin-bottom: 10px;
}

.doc-meta {
  font-size: 13.5px;
  color: var(--muted);
}

/* Section */
.section {
  margin-bottom: 48px;
  scroll-margin-top: 72px;
}

.section-label {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 1px;
  text-transform: uppercase;
  color: var(--muted);
  margin-bottom: 6px;
}

.section h2 {
  font-size: 18px;
  font-weight: 800;
  letter-spacing: -.4px;
  color: var(--text);
  margin-bottom: 16px;
  line-height: 1.3;
}

/* Part divider */
.part-divider {
  display: flex;
  align-items: center;
  gap: 16px;
  margin: 56px 0 40px;
}

.part-divider::before,
.part-divider::after {
  content: '';
  flex: 1;
  height: 1px;
  background: var(--border);
}

.part-divider span {
  font-size: 11.5px;
  font-weight: 700;
  letter-spacing: .6px;
  text-transform: uppercase;
  color: var(--muted);
  white-space: nowrap;
}

p {
  color: var(--muted);
  margin-bottom: 10px;
}

p:last-child {
  margin-bottom: 0;
}

ul {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 10px;
}

li {
  color: var(--muted);
  padding-left: 18px;
  position: relative;
}

li::before {
  content: '';
  position: absolute;
  left: 0;
  top: 11px;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: var(--border);
  border: 1.5px solid var(--muted);
}

a {
  color: var(--accent);
  text-decoration: underline;
  text-underline-offset: 2px;
}

a:hover {
  opacity: .65;
}

.doc-tabs a:hover,
.doc-tabs a.active {
  text-decoration: none;
}

/* ── Mobile ── */
@media (max-width: 768px) {
  .topbar {
    padding: 0 20px;
  }

  .layout {
    grid-template-columns: 1fr;
    padding: 28px 20px 64px;
    gap: 32px;
  }

  .toc {
    position: static;
  }
}

@media (max-width: 480px) {
  .layout {
    padding: 20px 16px 56px;
  }
}

.doc-date {
  margin-top: 8px;
  font-size: 13px;
  color: var(--muted);
}