:root {
  --bg: #0f1117;
  --surface: #171a23;
  --surface-2: #1f2430;
  --text: #e6e8ee;
  --muted: #9aa3b2;
  --accent: #6c8cff;
  --accent-soft: rgba(108, 140, 255, 0.12);
  --border: #272d3a;
  --radius: 14px;
  --maxw: 760px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica,
    Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji";
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

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

a:hover {
  text-decoration: underline;
}

.site-header {
  border-bottom: 1px solid var(--border);
  background: rgba(15, 17, 23, 0.85);
  backdrop-filter: blur(8px);
  position: sticky;
  top: 0;
  z-index: 10;
}

.site-header .inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 16px 20px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text);
  letter-spacing: -0.01em;
}

.brand span {
  color: var(--accent);
}

.nav a {
  color: var(--muted);
  margin-left: 18px;
  font-size: 0.92rem;
}

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

main {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 48px 20px 80px;
}

.hero {
  text-align: center;
  padding: 40px 0 24px;
}

.hero h1 {
  font-size: 2.2rem;
  margin: 0 0 12px;
  letter-spacing: -0.02em;
}

.hero p {
  color: var(--muted);
  max-width: 520px;
  margin: 0 auto;
  font-size: 1.05rem;
}

.cards {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 16px;
  margin-top: 40px;
}

@media (max-width: 560px) {
  .cards {
    grid-template-columns: 1fr;
  }
}

.card {
  display: block;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 24px;
  transition: border-color 0.15s ease, transform 0.15s ease;
}

.card:hover {
  border-color: var(--accent);
  text-decoration: none;
  transform: translateY(-2px);
}

.card h2 {
  margin: 0 0 8px;
  font-size: 1.2rem;
  color: var(--text);
}

.card p {
  margin: 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.doc h1 {
  font-size: 2rem;
  margin: 0 0 6px;
  letter-spacing: -0.02em;
}

.updated {
  color: var(--muted);
  font-size: 0.9rem;
  margin: 0 0 32px;
}

.doc h2 {
  font-size: 1.25rem;
  margin: 36px 0 10px;
  padding-top: 8px;
}

.doc h3 {
  font-size: 1.05rem;
  margin: 22px 0 8px;
  color: var(--text);
}

.doc p,
.doc li {
  color: #c8cdd9;
}

.doc ul {
  padding-left: 20px;
}

.doc li {
  margin-bottom: 6px;
}

.placeholder {
  background: var(--accent-soft);
  border-radius: 4px;
  padding: 0 4px;
  color: var(--accent);
  font-weight: 600;
}

.toc {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 18px 22px;
  margin: 0 0 36px;
}

.toc strong {
  display: block;
  margin-bottom: 8px;
  font-size: 0.85rem;
  text-transform: uppercase;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.toc ol {
  margin: 0;
  padding-left: 20px;
  columns: 2;
}

@media (max-width: 560px) {
  .toc ol {
    columns: 1;
  }
}

.toc a {
  color: #c8cdd9;
  font-size: 0.92rem;
}

.back {
  display: inline-block;
  margin-bottom: 24px;
  color: var(--muted);
  font-size: 0.9rem;
}

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

.site-footer .inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 24px 20px;
  display: flex;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}

.site-footer a {
  color: var(--muted);
}