:root {
  --ink: #111111;
  --paper: #ffffff;
  --muted: #6b6b6b;
  --subtle: #999999;
  --rule: #e4e4e4;
  --rule-light: #f0f0f0;
  --code-bg: #f5f5f5;
  --toc-width: 220px;
  --topbar-h: 54px;
  --accent: #111111;
}

* { box-sizing: border-box; }
html {
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--topbar-h) + 24px);
}

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: "Inter", system-ui, -apple-system, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 17px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
  text-rendering: optimizeLegibility;
}

/* ── Topbar ──────────────────────────────────────────────────────────────── */
.topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  height: var(--topbar-h);
  background: rgba(255, 255, 255, 0.92);
  backdrop-filter: saturate(180%) blur(12px);
  -webkit-backdrop-filter: saturate(180%) blur(12px);
  border-bottom: 1px solid var(--rule);
}

.topbar-inner {
  max-width: 1140px;
  margin: 0 auto;
  padding: 0 28px;
  height: 100%;
  display: flex;
  align-items: center;
  gap: 24px;
}

.site-name {
  font-size: 14px;
  font-weight: 600;
  letter-spacing: -0.01em;
  white-space: nowrap;
  flex-shrink: 0;
}

.topbar-right {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-left: auto;
}

/* Search */
.search-wrap {
  position: relative;
  display: flex;
  align-items: center;
}

.search-icon {
  position: absolute;
  left: 10px;
  width: 16px;
  height: 16px;
  color: var(--subtle);
  pointer-events: none;
  flex-shrink: 0;
}

#search {
  width: 240px;
  height: 34px;
  padding: 0 58px 0 34px;
  border: 1px solid var(--rule);
  border-radius: 8px;
  background: var(--rule-light);
  font-family: inherit;
  font-size: 13.5px;
  color: var(--ink);
  outline: none;
  transition: border-color 0.15s, background 0.15s, box-shadow 0.15s;
  -webkit-appearance: none;
  appearance: none;
}

#search:focus {
  border-color: #bbb;
  background: var(--paper);
  box-shadow: 0 0 0 3px rgba(0,0,0,0.06);
}

#search::placeholder { color: var(--subtle); }
#search::-webkit-search-cancel-button { display: none; }

.search-clear {
  position: absolute;
  right: 8px;
  padding: 2px 5px;
  font-family: inherit;
  font-size: 11px;
  font-weight: 500;
  color: var(--subtle);
  background: var(--rule-light);
  border: 1px solid var(--rule);
  border-radius: 4px;
  cursor: pointer;
  transition: color 0.1s;
  line-height: 1.4;
  user-select: none;
}
.search-clear:hover { color: var(--ink); }

.ghlink {
  font-size: 13.5px;
  font-weight: 500;
  letter-spacing: -0.01em;
  text-decoration: none;
  color: var(--muted);
  white-space: nowrap;
  transition: color 0.15s;
}
.ghlink:hover { color: var(--ink); }

/* ── Page layout ─────────────────────────────────────────────────────────── */
.page-layout {
  display: grid;
  grid-template-columns: var(--toc-width) 1fr;
  max-width: 1140px;
  margin: 0 auto;
  padding: 0 28px;
  gap: 56px;
  align-items: start;
}

/* ── TOC sidebar ─────────────────────────────────────────────────────────── */
.toc-sidebar {
  position: sticky;
  top: calc(var(--topbar-h) + 28px);
  max-height: calc(100vh - var(--topbar-h) - 56px);
  overflow-y: auto;
  padding-bottom: 24px;
  scrollbar-width: thin;
  scrollbar-color: var(--rule) transparent;
}

.toc-inner { padding-right: 8px; }

.toc-label {
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--subtle);
  margin: 28px 0 10px;
}

#toc {
  display: flex;
  flex-direction: column;
  gap: 1px;
}

#toc a {
  display: block;
  font-size: 13px;
  line-height: 1.45;
  text-decoration: none;
  color: var(--muted);
  border-radius: 5px;
  padding: 4px 8px;
  transition: color 0.12s, background 0.12s;
}

#toc a:hover {
  color: var(--ink);
  background: var(--rule-light);
}

#toc a.active {
  color: var(--ink);
  font-weight: 500;
  background: var(--rule-light);
}

#toc a.toc-h2 {
  font-weight: 500;
  margin-top: 8px;
  color: #444;
}

#toc a.toc-h3 {
  padding-left: 18px;
  font-size: 12.5px;
  color: var(--subtle);
}

#toc a.toc-h3:hover,
#toc a.toc-h3.active {
  color: var(--ink);
}

/* ── Content ─────────────────────────────────────────────────────────────── */
main.content {
  min-width: 0;
  max-width: 720px;
  padding-bottom: 96px;
  padding-top: 4px;
}

.content h1 {
  font-size: 2.4rem;
  font-weight: 700;
  letter-spacing: -0.035em;
  line-height: 1.1;
  margin: 52px 0 6px;
}

.content h2 {
  font-size: 1.4rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin: 64px 0 16px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--rule);
}

.content h3 {
  font-size: 1.05rem;
  font-weight: 600;
  letter-spacing: -0.01em;
  color: #333;
  margin: 36px 0 12px;
}

.content p { margin: 0 0 14px; }

.content a {
  color: var(--ink);
  text-decoration: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 2px;
  text-decoration-color: #c8c8c8;
  transition: text-decoration-color 0.15s;
}
.content a:hover { text-decoration-color: var(--ink); }

.content strong { font-weight: 600; }

.content ul {
  padding-left: 1.2em;
  margin: 0 0 14px;
}

.content li {
  margin: 9px 0;
  line-height: 1.55;
}

.content li::marker { color: #ccc; }

.content li li {
  color: var(--muted);
  font-size: 0.93em;
  margin: 4px 0;
}

code {
  font-family: "JetBrains Mono", ui-monospace, SFMono-Regular, Menlo, Consolas, monospace;
  font-size: 0.82em;
  background: var(--code-bg);
  padding: 0.12em 0.38em;
  border-radius: 4px;
}

hr {
  border: 0;
  border-top: 1px solid var(--rule);
  margin: 48px 0;
}

/* No results message */
.no-results {
  color: var(--muted);
  font-size: 15px;
  padding: 48px 0 24px;
}

/* ── Footer ──────────────────────────────────────────────────────────────── */
.site-footer {
  border-top: 1px solid var(--rule);
}

.footer-inner {
  max-width: 1140px;
  margin: 0 auto;
  padding: 24px 28px 56px;
  color: var(--muted);
  font-size: 13.5px;
}

.site-footer a { color: var(--muted); }
.site-footer a:hover { color: var(--ink); }

/* ── Responsive ──────────────────────────────────────────────────────────── */
@media (max-width: 900px) {
  .page-layout {
    grid-template-columns: 1fr;
    gap: 0;
    padding: 0 20px;
  }

  .toc-sidebar { display: none; }

  main.content { max-width: 100%; }

  .topbar-inner { padding: 0 20px; }
  .site-name { display: none; }

  #search { width: 200px; }
}

@media (max-width: 560px) {
  body { font-size: 16px; }
  .content h1 { font-size: 1.9rem; margin-top: 36px; }
  .content h2 { font-size: 1.25rem; }
  #search { width: 160px; }
  .footer-inner { padding: 20px 20px 48px; }
}