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

:root {
  --bg: #ffffff;
  --text: #111111;
  --muted: #555555;
  --border: #e5e5e5;
  --code-bg: #f4f4f4;
  --sidebar-w: 220px;
  --max-w: 980px;
}

body {
  margin: 0;
  font-family: ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
  background: var(--bg);
  color: var(--text);
  font-size: 0.97rem;
  line-height: 1.7;
}

a {
  color: var(--text);
  text-decoration: underline;
  text-underline-offset: 3px;
}

a:hover { color: #444; }

code, pre {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 0.875rem;
}

/* ── Nav ── */
nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 1.1rem 2rem;
  border-bottom: 1px solid var(--border);
}

.brand {
  font-weight: 700;
  font-size: 0.97rem;
  text-decoration: none;
  color: var(--text);
  letter-spacing: -0.01em;
}

.nav-links {
  display: flex;
  gap: 1.5rem;
  font-size: 0.875rem;
  color: var(--muted);
}

.nav-links a {
  color: var(--muted);
  text-decoration: none;
}

.nav-links a:hover,
.nav-links a.active {
  color: var(--text);
}

/* ── Layout ── */
.page {
  display: grid;
  grid-template-columns: var(--sidebar-w) 1fr;
  max-width: var(--max-w);
  margin: 0 auto;
  padding: 2.5rem 2rem;
  gap: 3rem;
  align-items: start;
}

/* ── Sidebar ── */
.sidebar {
  position: sticky;
  top: 2rem;
}

.sidebar-label {
  font-size: 0.72rem;
  font-weight: 700;
  letter-spacing: 0.09em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 0.75rem;
}

.sidebar nav {
  display: flex;
  flex-direction: column;
  gap: 0;
  padding: 0;
  border: none;
}

.sidebar nav a {
  display: block;
  padding: 0.38rem 0;
  font-size: 0.88rem;
  color: var(--muted);
  text-decoration: none;
  border-left: 2px solid transparent;
  padding-left: 0.75rem;
  margin-left: -0.75rem;
}

.sidebar nav a:hover {
  color: var(--text);
}

.sidebar nav a.active {
  color: var(--text);
  border-left-color: var(--text);
  font-weight: 500;
}

/* ── Content ── */
.content h1 {
  font-size: 1.75rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  line-height: 1.2;
  margin: 0 0 0.5rem;
}

.content .lead {
  color: var(--muted);
  font-size: 1rem;
  margin: 0 0 2.5rem;
  max-width: 60ch;
}

.content h2 {
  font-size: 1.05rem;
  font-weight: 700;
  margin: 2.25rem 0 0.6rem;
  padding-top: 2rem;
  border-top: 1px solid var(--border);
}

.content h2:first-of-type {
  margin-top: 0;
  padding-top: 0;
  border-top: none;
}

.content h3 {
  font-size: 0.95rem;
  font-weight: 700;
  margin: 1.5rem 0 0.4rem;
}

.content p {
  color: var(--muted);
  margin: 0 0 1rem;
}

.content ul,
.content ol {
  color: var(--muted);
  padding-left: 1.25rem;
  margin: 0 0 1rem;
}

.content li {
  margin-bottom: 0.3rem;
}

.content strong {
  color: var(--text);
  font-weight: 600;
}

.content code {
  background: var(--code-bg);
  padding: 0.15em 0.4em;
  border-radius: 4px;
  font-size: 0.83rem;
}

pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 1.1rem 1.25rem;
  overflow-x: auto;
  margin: 0 0 1.25rem;
}

pre code {
  background: none;
  padding: 0;
  font-size: 0.855rem;
  color: var(--text);
}

/* ── Table ── */
table {
  width: 100%;
  border-collapse: collapse;
  margin: 0 0 1.5rem;
  font-size: 0.9rem;
}

th {
  text-align: left;
  padding: 0.55rem 0.75rem;
  font-size: 0.78rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
  border-bottom: 1px solid var(--border);
}

td {
  padding: 0.6rem 0.75rem;
  border-bottom: 1px solid var(--border);
  color: var(--muted);
  vertical-align: top;
}

td:first-child {
  color: var(--text);
}

td code {
  font-size: 0.82rem;
}

/* ── Callout ── */
.callout {
  background: var(--code-bg);
  border-left: 3px solid var(--text);
  border-radius: 0 6px 6px 0;
  padding: 0.85rem 1rem;
  margin: 0 0 1.25rem;
  font-size: 0.9rem;
  color: var(--muted);
}

.callout strong {
  color: var(--text);
}

/* ── Step list ── */
.steps {
  counter-reset: step;
  list-style: none;
  padding: 0;
  margin: 0 0 1.5rem;
}

.steps li {
  counter-increment: step;
  display: flex;
  gap: 1rem;
  margin-bottom: 1.25rem;
  color: var(--muted);
}

.steps li::before {
  content: counter(step);
  flex-shrink: 0;
  width: 1.6rem;
  height: 1.6rem;
  border-radius: 50%;
  background: var(--code-bg);
  border: 1px solid var(--border);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 0.78rem;
  font-weight: 700;
  color: var(--text);
  margin-top: 0.15rem;
}

/* ── Responsive ── */
@media (max-width: 700px) {
  .page {
    grid-template-columns: 1fr;
    padding: 1.5rem 1rem;
  }

  .sidebar {
    position: static;
  }
}