:root {
  --bg: #0b1020;
  --bg-card: #141b2f;
  --text: #eef2ff;
  --muted: #9aa6c2;
  --accent: #6366f1;
  --accent-2: #38bdf8;
  --border: rgba(255, 255, 255, 0.08);
  --radius: 16px;
  --max: 820px;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: radial-gradient(1200px 600px at 10% -10%, #1e1b4b 0%, transparent 50%),
    radial-gradient(900px 500px at 100% 0%, #0c4a6e 0%, transparent 45%),
    var(--bg);
  color: var(--text);
  line-height: 1.7;
  min-height: 100vh;
}

a { color: var(--accent-2); text-decoration: none; }
a:hover { text-decoration: underline; }

.wrap {
  width: min(var(--max), calc(100% - 2rem));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 10;
  backdrop-filter: blur(12px);
  background: rgba(11, 16, 32, 0.75);
  border-bottom: 1px solid var(--border);
}
.site-header .wrap {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.9rem 0;
  gap: 1rem;
}
.brand {
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text);
  letter-spacing: 0.02em;
}
.site-header nav {
  display: flex;
  flex-wrap: wrap;
  gap: 0.85rem 1.1rem;
  font-size: 0.95rem;
}
.site-header nav a { color: var(--muted); }
.site-header nav a:hover,
.site-header nav a[aria-current="page"] {
  color: var(--text);
  text-decoration: none;
}

.hero { padding: 3.5rem 0 4rem; }
.eyebrow {
  color: var(--accent-2);
  font-size: 0.85rem;
  font-weight: 600;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  margin: 0 0 0.75rem;
}
.hero h1 {
  font-size: clamp(1.8rem, 4vw, 2.6rem);
  line-height: 1.2;
  margin: 0 0 1rem;
}
.lead {
  color: var(--muted);
  font-size: 1.05rem;
  max-width: 40rem;
  margin: 0 0 2.5rem;
}

.card-grid {
  display: grid;
  gap: 1rem;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
}
.card {
  display: block;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.35rem 1.25rem;
  color: inherit;
  transition: border-color 0.15s ease, transform 0.15s ease;
}
.card:hover {
  border-color: rgba(99, 102, 241, 0.55);
  transform: translateY(-2px);
  text-decoration: none;
}
.card-icon { font-size: 1.6rem; }
.card h2 {
  font-size: 1.15rem;
  margin: 0.6rem 0 0.4rem;
}
.card p {
  margin: 0;
  color: var(--muted);
  font-size: 0.95rem;
}

.doc { padding: 2.5rem 0 4rem; }
.doc header.page-title {
  margin-bottom: 2rem;
  padding-bottom: 1.25rem;
  border-bottom: 1px solid var(--border);
}
.doc h1 {
  font-size: clamp(1.6rem, 3vw, 2.1rem);
  margin: 0 0 0.5rem;
}
.meta {
  color: var(--muted);
  font-size: 0.9rem;
  margin: 0;
}
.doc section {
  margin: 1.75rem 0;
}
.doc h2 {
  font-size: 1.15rem;
  margin: 0 0 0.55rem;
  color: #c7d2fe;
}
.doc p, .doc li {
  color: #d4dced;
}
.doc ul { padding-left: 1.25rem; }
.doc li { margin: 0.35rem 0; }
.note {
  background: rgba(56, 189, 248, 0.08);
  border: 1px solid rgba(56, 189, 248, 0.25);
  border-radius: 12px;
  padding: 0.9rem 1rem;
  color: var(--muted);
  font-size: 0.95rem;
}
.lang-switch {
  display: inline-flex;
  gap: 0.5rem;
  margin-top: 0.75rem;
  font-size: 0.9rem;
}
.lang-switch a {
  padding: 0.2rem 0.55rem;
  border-radius: 999px;
  border: 1px solid var(--border);
  color: var(--muted);
}
.lang-switch a.active {
  background: rgba(99, 102, 241, 0.25);
  color: var(--text);
  border-color: rgba(99, 102, 241, 0.5);
  text-decoration: none;
}

.site-footer {
  border-top: 1px solid var(--border);
  padding: 1.5rem 0 2.5rem;
  color: var(--muted);
  font-size: 0.9rem;
}
.site-footer .muted { opacity: 0.75; font-size: 0.85rem; }

@media (max-width: 560px) {
  .site-header .wrap { flex-direction: column; align-items: flex-start; }
}