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

:root {
  --bg: #f5f7fa;
  --text: #1f2933;
  --header-bg: linear-gradient(135deg, #1d4ed8, #0f766e);
  --sidebar-bg: #0b1120;
  --sidebar-border: #111827;
  --sidebar-link: #e5e7eb;
  --sidebar-link-active: #fbbf24;
  --card-bg: #ffffff;
  --card-border: #e5e7eb;
  --code-bg: #e5e7eb;
  --pre-bg: #0f172a;
  --note-bg: #ecfeff;
  --note-border: #38bdf8;
  --warning-bg: #fff7ed;
  --warning-border: #f97316;
}

body.dark {
  --bg: #020617;
  --text: #e5e7eb;
  --header-bg: linear-gradient(135deg, #0f172a, #022c22);
  --sidebar-bg: #020617;
  --sidebar-border: #020617;
  --sidebar-link: #9ca3af;
  --sidebar-link-active: #facc15;
  --card-bg: #020617;
  --card-border: #1f2937;
  --code-bg: #111827;
  --pre-bg: #020617;
  --note-bg: #022c22;
  --note-border: #22c55e;
  --warning-bg: #451a03;
  --warning-border: #f97316;
}

body {
  margin: 0;
  font-family: system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI",
    sans-serif;
  line-height: 1.6;
  color: var(--text);
  background-color: var(--bg);
}

.site-header {
  padding: 1.5rem 1.75rem;
  background: var(--header-bg);
  color: #ffffff;
  box-shadow: 0 2px 4px rgba(15, 23, 42, 0.3);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
}

.site-header h1 {
  margin: 0 0 0.25rem;
  font-size: 1.8rem;
}

.site-header .tagline {
  margin: 0;
  font-size: 0.95rem;
  opacity: 0.9;
}

.header-controls {
  display: flex;
  align-items: center;
  gap: 0.75rem;
}

#global-search {
  padding: 0.3rem 0.6rem;
  border-radius: 4px;
  border: 1px solid rgba(255, 255, 255, 0.7);
  background: rgba(15, 23, 42, 0.1);
  color: #f9fafb;
  font-size: 0.85rem;
  min-width: 220px;
}

#global-search::placeholder {
  color: rgba(249, 250, 251, 0.8);
}

#global-search:focus {
  outline: none;
  border-color: #bfdbfe;
}

.theme-toggle {
  border-radius: 999px;
  border: 1px solid rgba(255, 255, 255, 0.6);
  background: rgba(15, 23, 42, 0.1);
  color: #ffffff;
  padding: 0.35rem 0.9rem;
  cursor: pointer;
  font-size: 0.85rem;
}

.theme-toggle:hover,
.theme-toggle:focus {
  background: rgba(15, 23, 42, 0.2);
}

.layout {
  display: grid;
  grid-template-columns: 260px minmax(0, 1fr);
  align-items: flex-start;
  gap: 0;
  min-height: calc(100vh - 80px);
}

.sidebar {
  padding: 1.5rem 1.25rem;
  background-color: var(--sidebar-bg);
  color: var(--sidebar-link);
  border-right: 1px solid var(--sidebar-border);
  position: sticky;
  top: 0;
  align-self: stretch;
  max-height: calc(100vh - 80px);
  overflow-y: auto;
}

.sidebar h2 {
  margin-top: 0;
  font-size: 1.1rem;
}

.sidebar ol {
  padding-left: 1.25rem;
  margin: 0.75rem 0 0;
}

.sidebar a {
  color: var(--sidebar-link);
  text-decoration: none;
}

.sidebar a:hover,
.sidebar a:focus {
  color: var(--sidebar-link-active);
  text-decoration: underline;
}

.sidebar a.active-link {
  color: var(--sidebar-link-active);
  font-weight: 600;
}

.content {
  padding: 1.75rem 2rem;
}

.content article {
  max-width: 900px;
  margin: 0 auto 3rem;
  background: var(--card-bg);
  padding: 1.75rem 1.75rem 2rem;
  border-radius: 8px;
  box-shadow: 0 1px 3px rgba(15, 23, 42, 0.16);
}

.content h1,
.content h2,
.content h3,
.content h4 {
  color: #111827;
}

.content h1 {
  margin-top: 0;
}

.content h2 {
  margin-top: 1.75rem;
}

.content h3 {
  margin-top: 1.5rem;
}

code {
  font-family: ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas,
    "Liberation Mono", "Courier New", monospace;
  font-size: 0.95em;
  background-color: var(--code-bg);
  padding: 0.1rem 0.25rem;
  border-radius: 3px;
}

pre {
  background-color: var(--pre-bg);
  color: #e5e7eb;
  padding: 1rem 1.25rem;
  border-radius: 6px;
  overflow-x: auto;
  font-size: 0.9rem;
  margin: 1rem 0;
}

pre code {
  background: transparent;
  padding: 0;
}

.token.comment {
  color: #9ca3af;
  font-style: italic;
}

.token.string {
  color: #bef264;
}

.token.number {
  color: #facc15;
}

.token.keyword {
  color: #38bdf8;
  font-weight: 600;
}

.token.function {
  color: #a5b4fc;
}

.toc {
  border-left: 3px solid #e5e7eb;
  padding-left: 1rem;
  margin: 1rem 0 1.5rem;
  font-size: 0.95rem;
}

.toc h3 {
  margin-top: 0;
}

.chapter-nav {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
  margin-top: 2rem;
  padding-top: 1.25rem;
  border-top: 1px solid #e5e7eb;
}

.chapter-nav a {
  display: inline-block;
  padding: 0.4rem 0.8rem;
  border-radius: 4px;
  background-color: #1d4ed8;
  color: #ffffff;
  text-decoration: none;
  font-size: 0.9rem;
}

.chapter-nav a.secondary {
  background-color: #374151;
}

.chapter-nav a:hover,
.chapter-nav a:focus {
  background-color: #2563eb;
}

.chapter-nav a.secondary:hover,
.chapter-nav a.secondary:focus {
  background-color: #4b5563;
}

.badge {
  display: inline-block;
  padding: 0.15rem 0.45rem;
  border-radius: 999px;
  background-color: #e0f2fe;
  color: #0369a1;
  font-size: 0.75rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.04em;
}

.note {
  border-left: 4px solid var(--note-border);
  background-color: var(--note-bg);
  padding: 0.75rem 1rem;
  border-radius: 4px;
  font-size: 0.9rem;
}

.warning {
  border-left: 4px solid var(--warning-border);
  background-color: var(--warning-bg);
}

.search-hit {
  outline: 2px solid #fbbf24;
  outline-offset: 3px;
  transition: outline-color 0.4s ease-out;
}

@media (max-width: 880px) {
  .layout {
    display: block;
  }

  .sidebar {
    position: static;
    max-height: none;
  }

  .content {
    padding: 1.25rem 1rem 2rem;
  }

  .content article {
    padding: 1.25rem 1.25rem 1.5rem;
  }
}