:root {
  --bg: #fbfaf8;
  --bg-raised: #ffffff;
  --bg-code: #f1efe9;
  --fg: #23211d;
  --fg-dim: #6b6a63;
  --border: #ddd9d0;
  --accent: #3457d5;
  --accent-soft: #e8ecfc;
  --font-body: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  --font-mono: "Courier New", Consolas, monospace;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg: #16150f;
    --bg-raised: #1e1c16;
    --bg-code: #201e18;
    --fg: #ecebe6;
    --fg-dim: #9a988f;
    --border: #38362c;
    --accent: #8ea2ff;
    --accent-soft: #232a4a;
  }
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: var(--font-body);
  line-height: 1.6;
}

code, pre, kbd {
  font-family: var(--font-mono);
}

a { color: var(--accent); }
a:hover { text-decoration: none; }

/* ---------- layout ---------- */

#page {
  display: flex;
  justify-content: center;
}

main {
  max-width: 760px;
  width: 100%;
  padding: 3rem 2rem 6rem;
}

#toc {
  position: sticky;
  top: 0;
  align-self: flex-start;
  height: 100vh;
  overflow-y: auto;
  flex: 0 0 260px;
  padding: 2.5rem 1.5rem;
  border-right: 1px solid var(--border);
  font-size: 0.85rem;
  scrollbar-color: var(--fg-dim) var(--bg);
  scrollbar-width: thin;
}

#toc::-webkit-scrollbar {
  width: 10px;
}

#toc::-webkit-scrollbar-track {
  background: var(--bg);
}

#toc::-webkit-scrollbar-thumb {
  background: var(--fg-dim);
  border: 2px solid var(--bg);
  border-radius: 6px;
}

#toc::-webkit-scrollbar-thumb:hover {
  background: var(--accent);
}

.toc-title {
  text-transform: uppercase;
  letter-spacing: 0.08em;
  font-size: 0.72rem;
  color: var(--fg-dim);
  margin-bottom: 0.75rem;
}

#toc ol {
  list-style: none;
  margin: 0;
  padding: 0;
}

#toc > ol > li {
  margin-bottom: 0.5rem;
}

#toc ol ol {
  margin-top: 0.35rem;
  padding-left: 1rem;
}

#toc ol ol li {
  margin-bottom: 0.3rem;
}

#toc a {
  color: var(--fg-dim);
  text-decoration: none;
  display: inline-block;
}

#toc a:hover {
  color: var(--accent);
}

@media (max-width: 900px) {
  #page { flex-direction: column; }
  #toc {
    position: static;
    height: auto;
    flex: none;
    border-right: none;
    border-bottom: 1px solid var(--border);
    padding: 1.5rem;
  }
  main { padding: 2rem 1.25rem 4rem; }
}

/* ---------- header ---------- */

header {
  margin-bottom: 3rem;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border);
}

.eyebrow {
  text-transform: uppercase;
  letter-spacing: 0.12em;
  font-size: 0.75rem;
  color: var(--accent);
  font-weight: 600;
  margin: 0 0 0.75rem;
}

h1 {
  font-size: 1.9rem;
  line-height: 1.25;
  margin: 0 0 1rem;
}

.lead {
  color: var(--fg-dim);
  font-size: 1.02rem;
  max-width: 62ch;
}

/* ---------- sections ---------- */

section {
  margin: 3rem 0;
  scroll-margin-top: 1.5rem;
}

h2 {
  font-size: 1.35rem;
  margin: 0 0 1rem;
  padding-top: 0.5rem;
  scroll-margin-top: 1.5rem;
}

h3 {
  font-size: 1.05rem;
  margin: 2rem 0 0.75rem;
  scroll-margin-top: 1.5rem;
}

.subtitle {
  font-weight: 400;
  color: var(--fg-dim);
  font-size: 0.85em;
}

p {
  margin: 0 0 1rem;
  max-width: 68ch;
}

ul, ol {
  padding-left: 1.3rem;
  max-width: 68ch;
}

li {
  margin-bottom: 0.5rem;
}

/* ---------- inline code ---------- */

code {
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: 3px;
  padding: 0.1em 0.35em;
  font-size: 0.88em;
}

/* ---------- code blocks ---------- */

.code-block {
  background: var(--bg-code);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 1rem 1.25rem;
  overflow-x: auto;
  font-size: 0.85rem;
  line-height: 1.55;
  margin: 0 0 1.25rem;
}

.code-block code {
  background: none;
  border: none;
  padding: 0;
  font-size: 1em;
  white-space: pre;
}

.code-block .c {
  color: var(--fg-dim);
  font-style: italic;
}

/* ---------- callout ---------- */

.callout {
  border-left: 3px solid var(--accent);
  background: var(--accent-soft);
  padding: 0.85rem 1.1rem;
  border-radius: 0 4px 4px 0;
  max-width: 68ch;
}

/* ---------- tables ---------- */

.table-wrap {
  overflow-x: auto;
  margin: 0 0 1.25rem;
}

.spec-table {
  border-collapse: collapse;
  width: 100%;
  font-size: 0.88rem;
}

.spec-table th,
.spec-table td {
  border: 1px solid var(--border);
  padding: 0.55rem 0.75rem;
  text-align: left;
  vertical-align: top;
}

.spec-table th {
  background: var(--bg-code);
  font-weight: 600;
  white-space: nowrap;
}

.spec-table td:first-child {
  white-space: nowrap;
}

.spec-table tbody tr:nth-child(even) {
  background: var(--bg-raised);
}

/* ---------- blockquote ---------- */

blockquote {
  margin: 0 0 1.25rem;
  padding: 1rem 1.25rem;
  border-left: 3px solid var(--border);
  background: var(--bg-raised);
  color: var(--fg-dim);
  max-width: 68ch;
  font-style: italic;
}

blockquote code {
  font-style: normal;
}

/* ---------- checklist ---------- */

.checklist {
  list-style: none;
  padding-left: 0;
}

.checklist li {
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
}

.checklist input {
  margin-top: 0.3rem;
  flex-shrink: 0;
}