:root {
  --bg: #ffffff;
  --fg: #1b1b1f;
  --muted: #6b7280;
  --accent: #2563eb;
  --border: #e5e7eb;
  --sidebar-bg: #f7f8fa;
  --code-bg: #f6f8fa;
  --sidebar-w: 320px;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 16px;
  line-height: 1.6;
}

.layout { display: flex; align-items: flex-start; }

.sidebar-wrap {
  width: var(--sidebar-w);
  min-width: var(--sidebar-w);
  height: 100vh;
  position: sticky;
  top: 0;
  overflow-y: auto;
  background: var(--sidebar-bg);
  border-right: 1px solid var(--border);
  padding: 1rem 0.75rem;
}

.content {
  flex: 1 1 auto;
  max-width: 860px;
  padding: 2rem 2.5rem 4rem;
  margin: 0 auto;
  overflow-x: auto;
}

/* Navigation */
.sidebar .nav-section {
  font-size: 0.8rem;
  text-transform: uppercase;
  letter-spacing: 0.04em;
  color: var(--muted);
  margin: 1.1rem 0 0.3rem;
}
.sidebar .nav-link {
  display: block;
  padding: 0.15rem 0.4rem;
  color: var(--fg);
  text-decoration: none;
  border-radius: 4px;
  font-size: 0.9rem;
}
.sidebar .nav-link:hover { background: #e8edf5; }
.sidebar .nav-nested { padding-left: 1.4rem; color: var(--muted); font-size: 0.85rem; }
.sidebar .nav-active { background: var(--accent); color: #fff; }
.sidebar .nav-active:hover { background: var(--accent); }
.sidebar .nav-broken { color: #b91c1c; cursor: help; }

/* Content typography */
.content h1 { font-size: 1.9rem; line-height: 1.2; margin-top: 0; }
.content h2 { font-size: 1.45rem; margin-top: 2rem; border-bottom: 1px solid var(--border); padding-bottom: 0.3rem; }
.content h3 { font-size: 1.15rem; margin-top: 1.6rem; }
.content a { color: var(--accent); }

.content table {
  border-collapse: collapse;
  width: 100%;
  margin: 1rem 0;
  font-size: 0.9rem;
}
.content th, .content td {
  border: 1px solid var(--border);
  padding: 0.45rem 0.6rem;
  text-align: left;
  vertical-align: top;
}
.content th { background: var(--sidebar-bg); }

.content blockquote {
  border-left: 4px solid var(--border);
  margin: 1rem 0;
  padding: 0.2rem 1rem;
  color: var(--muted);
}

/* Code */
.content pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 0.9rem 1rem;
  overflow-x: auto;
  font-size: 0.85rem;
  line-height: 1.45;
}
.content code {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
}
.content :not(pre) > code {
  background: var(--code-bg);
  padding: 0.1rem 0.3rem;
  border-radius: 4px;
  font-size: 0.85em;
}
/* Plain/pseudocode and ASCII-art diagrams: preserve whitespace exactly */
.content pre.code-plain code { white-space: pre; }
.content pre.mermaid {
  background: transparent;
  border: none;
  text-align: center;
}

.page-footer {
  margin-top: 3rem;
  padding-top: 1rem;
  border-top: 1px solid var(--border);
  color: var(--muted);
  font-size: 0.85rem;
}

/* Mobile nav toggle */
#nav-toggle {
  display: none;
  position: fixed;
  top: 0.6rem;
  right: 0.6rem;
  z-index: 20;
  background: var(--accent);
  color: #fff;
  border: none;
  border-radius: 6px;
  padding: 0.4rem 0.7rem;
  font-size: 0.9rem;
  cursor: pointer;
}

@media (max-width: 800px) {
  #nav-toggle { display: block; }
  .sidebar-wrap {
    position: fixed;
    z-index: 15;
    transform: translateX(-100%);
    transition: transform 0.2s ease;
  }
  body.nav-open .sidebar-wrap { transform: translateX(0); }
  .content { padding: 3rem 1.2rem 4rem; }
}