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

:root {
  --sidebar-w: 260px;
  --bg: #fff;
  --fg: #18181b;
  --fg-muted: #52525b;
  --sidebar-bg: #0f0d1e;
  --sidebar-fg: #c7c7d8;
  --sidebar-fg-muted: #7c7c9a;
  --accent: #6366f1;
  --accent-dim: #4f46e5;
  --border: #e4e4e7;
  --code-bg: #f4f4f5;
  --code-fg: #18181b;
  --radius: 6px;
  --font: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
  --mono: 'SF Mono', 'Fira Code', 'Fira Mono', Menlo, Consolas, monospace;
}

html { font-size: 16px; scroll-behavior: smooth; }
body {
  font-family: var(--font);
  color: var(--fg);
  background: var(--bg);
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

/* Layout */
.layout { display: flex; min-height: 100vh; }

/* Sidebar */
.sidebar {
  width: var(--sidebar-w);
  min-width: var(--sidebar-w);
  background: var(--sidebar-bg);
  color: var(--sidebar-fg);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 40;
  overflow-y: auto;
  padding: 28px 24px 24px;
}

.sidebar-header { margin-bottom: 32px; }
.brand {
  font-size: 1.5rem;
  font-weight: 700;
  color: #fff;
  text-decoration: none;
  letter-spacing: -0.02em;
}
.brand:hover { color: var(--accent); }
.tagline {
  font-size: 0.8125rem;
  color: var(--sidebar-fg-muted);
  margin-top: 6px;
  line-height: 1.5;
}

/* Navigation */
.sidebar-nav { flex: 1; display: flex; flex-direction: column; gap: 2px; }

.nav-link {
  display: block;
  padding: 6px 12px;
  border-radius: var(--radius);
  color: var(--sidebar-fg);
  text-decoration: none;
  font-size: 0.875rem;
  transition: background 0.15s, color 0.15s;
  margin: 0 -12px;
}
.nav-link:hover { background: rgba(255,255,255,0.06); color: #fff; }
.nav-link.active {
  background: rgba(99,102,241,0.15);
  color: var(--accent);
  font-weight: 600;
}

.nav-section {
  font-size: 0.6875rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.08em;
  color: var(--sidebar-fg-muted);
  padding: 16px 12px 4px;
}
.nav-section:first-child { padding-top: 0; }

.nav-group { display: none; }
.nav-group.open { display: block; }
.nav-group .nav-link { padding-left: 24px; font-size: 0.8125rem; }

/* Sidebar footer */
.sidebar-footer {
  margin-top: 24px;
  padding-top: 20px;
  border-top: 1px solid rgba(255,255,255,0.08);
  display: flex;
  flex-direction: column;
  gap: 6px;
}
.sidebar-link {
  color: var(--sidebar-fg-muted);
  text-decoration: none;
  font-size: 0.8125rem;
  transition: color 0.15s;
}
.sidebar-link:hover { color: #fff; }

/* Content area */
.content {
  margin-left: var(--sidebar-w);
  flex: 1;
  min-width: 0;
  padding: 48px 56px 96px;
  max-width: 780px;
}

/* Mobile menu toggle */
.menu-toggle { display: none; }
.menu-btn {
  display: none;
  flex-direction: column;
  gap: 5px;
  cursor: pointer;
  padding: 8px;
  margin-bottom: 16px;
  width: 36px;
}
.menu-btn span {
  display: block;
  height: 2px;
  background: var(--fg);
  border-radius: 2px;
  transition: transform 0.2s, opacity 0.2s;
}
.menu-overlay { display: none; }

/* Typography */
.content h1 { font-size: 2rem; font-weight: 700; letter-spacing: -0.03em; margin-bottom: 0.5em; line-height: 1.3; }
.content h2 { font-size: 1.375rem; font-weight: 600; margin: 2.5em 0 0.6em; padding-bottom: 0.3em; border-bottom: 1px solid var(--border); }
.content h3 { font-size: 1.125rem; font-weight: 600; margin: 1.8em 0 0.4em; }
.content h4 { font-size: 1rem; font-weight: 600; margin: 1.5em 0 0.3em; }

.content p { margin: 0.8em 0; }
.content a { color: var(--accent-dim); text-decoration: none; }
.content a:hover { text-decoration: underline; }
.content strong { font-weight: 600; color: #09090b; }

.content ul, .content ol { padding-left: 1.5em; margin: 0.8em 0; }
.content li { margin: 0.25em 0; }
.content li > p { margin: 0.2em 0; }

.content blockquote {
  border-left: 3px solid var(--accent);
  margin: 1.2em 0;
  padding: 0.5em 1em;
  color: var(--fg-muted);
  background: #fafafa;
  border-radius: 0 var(--radius) var(--radius) 0;
}
.content blockquote p { margin: 0.3em 0; }

.content hr { border: none; border-top: 1px solid var(--border); margin: 2em 0; }

/* Code */
.content code {
  font-family: var(--mono);
  font-size: 0.875em;
  background: var(--code-bg);
  color: var(--code-fg);
  padding: 0.15em 0.4em;
  border-radius: 4px;
  font-weight: 500;
}

.content pre {
  background: #18181b;
  color: #e4e4e7;
  padding: 16px 20px;
  border-radius: var(--radius);
  overflow-x: auto;
  margin: 1.2em 0;
  font-size: 0.875rem;
  line-height: 1.6;
}
.content pre code {
  background: none;
  color: inherit;
  padding: 0;
  font-size: inherit;
  font-weight: 400;
}

/* Tables */
.content table {
  width: 100%;
  border-collapse: collapse;
  margin: 1.2em 0;
  font-size: 0.9375rem;
}
.content th {
  text-align: left;
  font-weight: 600;
  padding: 8px 12px;
  border-bottom: 2px solid var(--border);
  color: var(--fg-muted);
  font-size: 0.8125rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.content td {
  padding: 8px 12px;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

/* Images */
.content img { max-width: 100%; border-radius: var(--radius); }

/* Responsive */
@media (max-width: 768px) {
  :root { --sidebar-w: 240px; }

  .sidebar {
    transform: translateX(-100%);
    transition: transform 0.25s ease;
  }
  .menu-toggle:checked ~ .layout .sidebar {
    transform: translateX(0);
  }
  .menu-toggle:checked ~ .layout .menu-overlay {
    display: block;
    position: fixed;
    inset: 0;
    background: rgba(0,0,0,0.4);
    z-index: 30;
  }

  .content { margin-left: 0; padding: 24px 20px 64px; max-width: 100%; }
  .menu-btn { display: flex; }

  .content h1 { font-size: 1.625rem; }
  .content h2 { font-size: 1.25rem; }
}

/* ─── Hero links ─── */
.hero-links { margin: 1.5rem 0; display: flex; gap: 0.75rem; flex-wrap: wrap; }
.button { display: inline-block; padding: 0.6rem 1.2rem; border-radius: 4px; text-decoration: none; font-weight: 600; font-size: 0.95rem; }
.button.primary { background: #2563eb; color: #fff; }
.button.primary:hover { background: #1d4ed8; }
.button.secondary { border: 1px solid var(--line-strong); color: var(--ink); }
.button.secondary:hover { background: var(--surface-2); }