/* ── Base Reset & Typography ─────────────────────────────────────── */
*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --max-width: 820px;
  --sidebar-width: 260px;
  --header-height: 56px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  --color-bg: #ffffff;
  --color-text: #1a1a1a;
  --color-muted: #6b7280;
  --color-border: #e5e7eb;
  --color-link: #2563eb;
  --color-link-hover: #1d4ed8;
  --color-code-bg: #f3f4f6;
  --color-accent: #ef4444;
  --color-sidebar-bg: #f9fafb;
  --color-highlight: #fde68a;
  --color-highlight-active: #f59e0b;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--header-height) + 16px);
}

body {
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.7;
  color: var(--color-text);
  background: var(--color-bg);
}

/* ── Header ──────────────────────────────────────────────────────── */
.site-header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: var(--header-height);
  background: var(--color-bg);
  border-bottom: 1px solid var(--color-border);
  display: flex;
  align-items: center;
  padding: 0 20px;
  z-index: 100;
  gap: 12px;
}

.site-header .logo {
  font-weight: 700;
  font-size: 15px;
  color: var(--color-accent);
  text-decoration: none;
  white-space: nowrap;
}

.site-header nav {
  display: flex;
  gap: 16px;
  flex-wrap: wrap;
}

.site-header nav a {
  font-size: 14px;
  color: var(--color-muted);
  text-decoration: none;
  white-space: nowrap;
}

.site-header nav a:hover,
.site-header nav a.active {
  color: var(--color-link);
}

.hamburger {
  display: none;
  background: none;
  border: none;
  font-size: 22px;
  cursor: pointer;
  padding: 4px 8px;
  color: var(--color-text);
}

/* ── Search Bar (in header) ──────────────────────────────────────── */
.search-bar {
  margin-left: auto;
  display: flex;
  align-items: center;
  gap: 6px;
  flex-shrink: 0;
}

.search-bar input {
  font-size: 13px;
  padding: 4px 8px;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  width: 180px;
  font-family: var(--font-sans);
}

.search-bar .search-info {
  font-size: 12px;
  color: var(--color-muted);
  white-space: nowrap;
}

.search-bar button {
  font-size: 13px;
  padding: 3px 8px;
  border: 1px solid var(--color-border);
  border-radius: 4px;
  background: var(--color-bg);
  cursor: pointer;
  font-family: var(--font-sans);
  color: var(--color-text);
}

.search-bar button:hover {
  background: var(--color-code-bg);
}

/* ── Layout ──────────────────────────────────────────────────────── */
.layout {
  display: flex;
  margin-top: var(--header-height);
  min-height: calc(100vh - var(--header-height));
}

/* ── Sidebar ─────────────────────────────────────────────────────── */
.sidebar {
  position: fixed;
  top: var(--header-height);
  left: 0;
  bottom: 0;
  width: var(--sidebar-width);
  background: var(--color-sidebar-bg);
  border-right: 1px solid var(--color-border);
  overflow-y: auto;
  padding: 16px 0;
  z-index: 90;
  transition: transform 0.2s ease;
}

.sidebar-section {
  padding: 0 16px;
  margin-bottom: 20px;
}

.sidebar-section h3 {
  font-size: 11px;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--color-muted);
  margin-bottom: 8px;
}

.sidebar-section ul {
  list-style: none;
}

.sidebar-section li a {
  display: block;
  font-size: 13px;
  color: var(--color-text);
  text-decoration: none;
  padding: 3px 0;
  line-height: 1.4;
}

.sidebar-section li a:hover {
  color: var(--color-link);
}

.sidebar-section li.toc-h3 a {
  padding-left: 12px;
  font-size: 12px;
  color: var(--color-muted);
}

/* ── Main Content ────────────────────────────────────────────────── */
.main-content {
  margin-left: var(--sidebar-width);
  flex: 1;
  padding: 32px 40px 64px;
  max-width: calc(var(--max-width) + 80px);
}

#content {
  max-width: var(--max-width);
}

.loading {
  color: var(--color-muted);
  font-style: italic;
}

.error {
  color: var(--color-accent);
  background: #fef2f2;
  border: 1px solid #fecaca;
  padding: 16px;
  border-radius: 6px;
}

/* ── Markdown Rendered Content ───────────────────────────────────── */
#content h1 {
  font-size: 1.8em;
  margin: 1.6em 0 0.6em;
  padding-bottom: 0.3em;
  border-bottom: 1px solid var(--color-border);
  line-height: 1.3;
}

#content h1:first-child {
  margin-top: 0;
}

#content h2 {
  font-size: 1.4em;
  margin: 1.4em 0 0.5em;
  line-height: 1.3;
}

#content h3 {
  font-size: 1.15em;
  margin: 1.2em 0 0.4em;
}

#content p {
  margin: 0.6em 0;
}

#content ul,
#content ol {
  margin: 0.6em 0;
  padding-left: 1.6em;
}

#content li {
  margin: 0.25em 0;
}

#content blockquote {
  border-left: 3px solid var(--color-accent);
  padding: 0.4em 1em;
  margin: 0.8em 0;
  color: var(--color-muted);
  background: var(--color-code-bg);
  border-radius: 0 4px 4px 0;
}

#content code {
  font-family: var(--font-mono);
  font-size: 0.88em;
  background: var(--color-code-bg);
  padding: 0.15em 0.4em;
  border-radius: 3px;
}

#content pre {
  background: var(--color-code-bg);
  padding: 14px 18px;
  border-radius: 6px;
  overflow-x: auto;
  margin: 0.8em 0;
}

#content pre code {
  background: none;
  padding: 0;
}

#content hr {
  border: none;
  border-top: 1px solid var(--color-border);
  margin: 1.5em 0;
}

#content a {
  color: var(--color-link);
}

#content a:hover {
  color: var(--color-link-hover);
}

#content strong {
  font-weight: 600;
}

/* ── Heading Anchor Links ────────────────────────────────────────── */
.heading-anchor {
  position: relative;
}

.heading-anchor .copy-link {
  display: inline-block;
  margin-left: 6px;
  font-size: 0.65em;
  color: var(--color-muted);
  cursor: pointer;
  opacity: 0;
  transition: opacity 0.15s;
  vertical-align: middle;
  text-decoration: none;
}

.heading-anchor:hover .copy-link {
  opacity: 1;
}

.copy-link.copied {
  color: #16a34a;
}

/* ── Search Highlights ───────────────────────────────────────────── */
mark.search-highlight {
  background: var(--color-highlight);
  padding: 1px 2px;
  border-radius: 2px;
}

mark.search-highlight.active {
  background: var(--color-highlight-active);
  color: #fff;
}

/* ── Mobile ──────────────────────────────────────────────────────── */
@media (max-width: 768px) {
  .hamburger {
    display: block;
  }

  .site-header nav {
    display: none;
  }

  .sidebar {
    transform: translateX(-100%);
  }

  .sidebar.open {
    transform: translateX(0);
  }

  .main-content {
    margin-left: 0;
    padding: 24px 20px 48px;
  }

  .search-bar input {
    width: 120px;
  }
}

/* ── Print ───────────────────────────────────────────────────────── */
@media print {
  .site-header,
  .sidebar,
  .search-bar,
  .hamburger,
  .copy-link {
    display: none !important;
  }

  .layout {
    display: block;
    margin-top: 0;
  }

  .main-content {
    margin-left: 0;
    padding: 0;
    max-width: 100%;
  }

  #content h1 {
    page-break-before: always;
  }

  #content h1:first-child {
    page-break-before: avoid;
  }

  #content h2 {
    page-break-before: always;
  }

  #content {
    max-width: 100%;
  }
}