:root {
  --bg: #ffffff;
  --text: #1f2933;
  --muted: #6b7280;
  --border: #e5e7eb;
  --sidebar-bg: #f7f8fa;
  --accent: #2563eb;
  --code-bg: #f3f4f6;
  --max-width: 780px;
}

* { box-sizing: border-box; }

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

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

/* Sidebar */
.sidebar {
  width: 240px;
  flex-shrink: 0;
  background: var(--sidebar-bg);
  border-right: 1px solid var(--border);
  padding: 1.5rem 1rem;
}

.sidebar .brand {
  font-weight: 700;
  font-size: 1.05rem;
  margin: 0 0 0.25rem;
}

.sidebar .brand-sub {
  color: var(--muted);
  font-size: 0.8rem;
  margin: 0 0 1.5rem;
}

.sidebar nav a {
  display: block;
  padding: 0.4rem 0.6rem;
  margin-bottom: 0.15rem;
  border-radius: 6px;
  color: var(--text);
  text-decoration: none;
  font-size: 0.92rem;
}

.sidebar nav a:hover { background: #eceef1; }
.sidebar nav a.active {
  background: var(--accent);
  color: #fff;
  font-weight: 600;
}

/* Content */
.content {
  flex: 1;
  padding: 2.5rem 2rem;
  max-width: var(--max-width);
}

.content h1 {
  margin-top: 0;
  font-size: 2rem;
}

.content h2 {
  margin-top: 2rem;
  border-bottom: 1px solid var(--border);
  padding-bottom: 0.3rem;
}

.content code {
  background: var(--code-bg);
  padding: 0.15em 0.4em;
  border-radius: 4px;
  font-size: 0.9em;
}

.content pre {
  background: var(--code-bg);
  padding: 1rem;
  border-radius: 8px;
  overflow-x: auto;
}

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

.callout {
  border-left: 4px solid var(--accent);
  background: #eff6ff;
  padding: 0.75rem 1rem;
  border-radius: 0 6px 6px 0;
  margin: 1.25rem 0;
}

.callout.warn {
  border-left-color: #d97706;
  background: #fffbeb;
}

table {
  border-collapse: collapse;
  width: 100%;
  margin: 1.25rem 0;
}

th, td {
  border: 1px solid var(--border);
  padding: 0.5rem 0.75rem;
  text-align: left;
}

th { background: var(--sidebar-bg); }

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

/* Small screens: stack the sidebar on top */
@media (max-width: 640px) {
  .layout { flex-direction: column; }
  .sidebar { width: 100%; border-right: none; border-bottom: 1px solid var(--border); }
  .content { padding: 1.5rem 1.25rem; }
}