:root {
  --bg: #0b1020;
  --bg-soft: #101a33;
  --card: #131e3b;
  --card-hover: #18264d;
  --border: #22315a;
  --text: #e8edf7;
  --text-muted: #9aa7c7;
  --accent: #4d6bfe;
  --accent-soft: rgba(77, 107, 254, 0.14);
  --cyan: #22d3ee;
  --code-bg: #0a0f22;
  --danger: #f87171;
  --radius: 14px;
  --maxw: 1080px;
  --font: "Inter", "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC",
    "Source Han Sans SC", system-ui, -apple-system, "Segoe UI", sans-serif;
  --mono: "JetBrains Mono", "SFMono-Regular", Consolas, "Liberation Mono",
    Menlo, monospace;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 16px;
  line-height: 1.75;
  -webkit-font-smoothing: antialiased;
}

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

a:hover {
  text-decoration: underline;
}

.container {
  width: min(var(--maxw), 92%);
  margin: 0 auto;
}

/* Header */
.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background: rgba(11, 16, 32, 0.92);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  min-height: 64px;
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  color: var(--text);
  font-weight: 700;
  font-size: 18px;
}

.brand:hover {
  text-decoration: none;
}

.brand-logo {
  width: 30px;
  height: 30px;
  border-radius: 8px;
  background: linear-gradient(135deg, var(--accent), #7b5cff);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 800;
  font-size: 15px;
}

.site-nav ul {
  display: flex;
  align-items: center;
  gap: 4px;
  list-style: none;
  margin: 0;
  padding: 0;
}

.site-nav a {
  display: inline-block;
  padding: 8px 12px;
  border-radius: 8px;
  color: var(--text-muted);
  font-size: 14.5px;
}

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

.site-nav a[aria-current="page"] {
  color: #fff;
  background: var(--accent-soft);
  font-weight: 600;
}

.nav-toggle {
  display: none;
  background: none;
  border: 1px solid var(--border);
  color: var(--text);
  border-radius: 8px;
  padding: 6px 12px;
  font-size: 14px;
  cursor: pointer;
}

/* Hero */
.hero {
  padding: 64px 0 40px;
  background:
    radial-gradient(700px 300px at 20% -10%, rgba(77, 107, 254, 0.25), transparent 70%),
    radial-gradient(600px 260px at 90% 0%, rgba(34, 211, 238, 0.12), transparent 70%);
}

.hero h1 {
  margin: 0 0 16px;
  font-size: clamp(30px, 5vw, 48px);
  line-height: 1.2;
  letter-spacing: -0.02em;
}

.hero p.lead {
  font-size: clamp(16px, 2vw, 19px);
  color: var(--text-muted);
  max-width: 720px;
  margin: 0 0 28px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.btn {
  display: inline-block;
  padding: 11px 22px;
  border-radius: 10px;
  font-weight: 600;
  font-size: 15px;
  border: 1px solid transparent;
}

.btn-primary {
  background: var(--accent);
  color: #fff;
}

.btn-primary:hover {
  background: #5f7bff;
  text-decoration: none;
}

.btn-ghost {
  border-color: var(--border);
  color: var(--text);
  background: transparent;
}

.btn-ghost:hover {
  background: var(--accent-soft);
  text-decoration: none;
}

/* Sections and cards */
section {
  padding: 40px 0;
}

.section-title {
  font-size: clamp(22px, 3vw, 30px);
  margin: 0 0 8px;
  letter-spacing: -0.01em;
}

.section-sub {
  color: var(--text-muted);
  margin: 0 0 28px;
  max-width: 720px;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 18px;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 22px;
  transition: transform 0.15s ease, border-color 0.15s ease, background 0.15s ease;
}

.card:hover {
  transform: translateY(-2px);
  border-color: var(--accent);
  background: var(--card-hover);
}

.card h3 {
  margin: 0 0 8px;
  font-size: 18px;
}

.card h3 a {
  color: var(--text);
}

.card h3 a:hover {
  color: var(--cyan);
}

.card p {
  margin: 0;
  color: var(--text-muted);
  font-size: 14.5px;
}

.card .tag {
  display: inline-block;
  margin-top: 12px;
  font-size: 12.5px;
  color: var(--cyan);
}

/* Article layout */
.article-wrap {
  padding: 48px 0 64px;
}

article {
  max-width: 820px;
}

article h1 {
  font-size: clamp(28px, 4vw, 40px);
  line-height: 1.25;
  letter-spacing: -0.02em;
  margin: 12px 0 16px;
}

article h2 {
  font-size: clamp(21px, 2.6vw, 26px);
  margin: 44px 0 12px;
  padding-top: 8px;
  border-top: 1px solid var(--border);
}

article h3 {
  font-size: 19px;
  margin: 32px 0 8px;
}

article p,
article li {
  color: #cdd6ea;
}

article ul,
article ol {
  padding-left: 22px;
}

article li + li {
  margin-top: 6px;
}

.meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  color: var(--text-muted);
  font-size: 13.5px;
  margin-bottom: 28px;
}

.meta time {
  color: var(--text-muted);
}

.updated-note,
.disclaimer-note {
  background: var(--accent-soft);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 12px 16px;
  font-size: 14px;
  color: var(--text-muted);
  margin: 24px 0;
}

/* Tables */
.table-wrap {
  overflow-x: auto;
  margin: 20px 0;
}

table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14.5px;
  background: var(--card);
  border-radius: 12px;
  overflow: hidden;
}

th,
td {
  text-align: left;
  padding: 12px 14px;
  border-bottom: 1px solid var(--border);
  vertical-align: top;
}

th {
  background: var(--bg-soft);
  color: var(--text);
  font-weight: 600;
  white-space: nowrap;
}

tbody tr:last-child td {
  border-bottom: none;
}

/* Code blocks */
pre {
  background: var(--code-bg);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px 18px;
  overflow-x: auto;
  font-size: 13.5px;
  line-height: 1.65;
}

code {
  font-family: var(--mono);
  background: var(--accent-soft);
  border-radius: 5px;
  padding: 2px 6px;
  font-size: 0.92em;
}

pre code {
  background: none;
  padding: 0;
  color: #dbe4ff;
}

.cmd {
  display: block;
  margin-bottom: 6px;
  color: var(--cyan);
}

/* FAQ */
.faq-item {
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--card);
  padding: 20px 22px;
  margin-bottom: 14px;
}

.faq-item summary {
  cursor: pointer;
  font-weight: 600;
  font-size: 16px;
}

.faq-item p {
  color: #cdd6ea;
}

/* Callout */
.callout {
  border-left: 3px solid var(--accent);
  background: var(--accent-soft);
  border-radius: 0 10px 10px 0;
  padding: 14px 18px;
  margin: 22px 0;
  font-size: 15px;
}

.callout.warn {
  border-left-color: var(--danger);
  background: rgba(248, 113, 113, 0.08);
}

/* Breadcrumb */
.breadcrumb {
  font-size: 13.5px;
  color: var(--text-muted);
  margin-bottom: 8px;
}

.breadcrumb a {
  color: var(--text-muted);
}

.breadcrumb a:hover {
  color: var(--cyan);
}

.breadcrumb span {
  color: var(--text-muted);
}

/* Footer */
.site-footer {
  border-top: 1px solid var(--border);
  margin-top: 48px;
  padding: 36px 0 28px;
  background: var(--bg-soft);
  color: var(--text-muted);
  font-size: 14px;
}

.footer-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(200px, 1fr));
  gap: 24px;
  margin-bottom: 20px;
}

.footer-grid h4 {
  margin: 0 0 10px;
  color: var(--text);
  font-size: 15px;
}

.footer-grid ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.footer-grid li + li {
  margin-top: 6px;
}

.footer-note {
  border-top: 1px solid var(--border);
  padding-top: 18px;
  font-size: 13px;
  color: var(--text-muted);
}

.back-to-top {
  display: inline-block;
  margin-top: 12px;
  font-size: 13.5px;
}

/* 404 */
.error-page {
  text-align: center;
  padding: 100px 0;
}

.error-page h1 {
  font-size: 80px;
  margin: 0;
  color: var(--accent);
}

.error-page p {
  color: var(--text-muted);
  margin-bottom: 24px;
}

/* Responsive */
@media (max-width: 760px) {
  .nav-toggle {
    display: inline-block;
  }

  .site-nav {
    display: none;
    position: absolute;
    top: 64px;
    left: 0;
    right: 0;
    background: var(--bg-soft);
    border-bottom: 1px solid var(--border);
    padding: 12px 4%;
  }

  .site-nav.open {
    display: block;
  }

  .site-nav ul {
    flex-direction: column;
    align-items: stretch;
  }

  .hero {
    padding: 44px 0 28px;
  }
}