:root {
  color-scheme: light;
  --bg: #f6f7fb;
  --panel: rgba(255, 255, 255, 0.78);
  --panel-strong: rgba(255, 255, 255, 0.92);
  --text: #10131a;
  --muted: #5c6676;
  --line: rgba(16, 19, 26, 0.08);
  --accent: #2563eb;
  --accent-soft: rgba(37, 99, 235, 0.08);
  --shadow: 0 20px 60px rgba(15, 23, 42, 0.08);
  --radius: 24px;
}

* { box-sizing: border-box; }
html, body { margin: 0; padding: 0; }
body {
  font-family: -apple-system, BlinkMacSystemFont, 'SF Pro Text', 'PingFang SC', 'Helvetica Neue', sans-serif;
  background:
    radial-gradient(circle at top, rgba(59, 130, 246, 0.12), transparent 28%),
    linear-gradient(180deg, #fbfcff 0%, var(--bg) 100%);
  color: var(--text);
  line-height: 1.72;
}

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

.shell {
  width: min(1040px, calc(100% - 32px));
  margin: 0 auto;
}

header.hero {
  padding: 72px 0 32px;
}

.topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-bottom: 28px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  font-weight: 600;
  color: var(--text);
}

.brand-mark {
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(255,255,255,0.95) 0%, rgba(191,219,254,0.85) 36%, rgba(59,130,246,0.28) 100%);
  box-shadow: 0 0 32px rgba(59, 130, 246, 0.28);
}

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

.nav a {
  padding: 10px 14px;
  border-radius: 999px;
  background: rgba(255,255,255,0.68);
  border: 1px solid var(--line);
  color: var(--muted);
}

.panel {
  background: var(--panel);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
  border-radius: var(--radius);
  backdrop-filter: blur(18px);
}

.hero-card {
  padding: 40px;
}

.hero-card h1 {
  margin: 0 0 16px;
  font-size: clamp(32px, 5vw, 52px);
  line-height: 1.08;
  letter-spacing: -0.03em;
}

.hero-card p,
.hero-card li,
.doc p,
.doc li,
.footer {
  color: var(--muted);
}

.badges {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 18px 0 0;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 14px;
  background: var(--accent-soft);
  border-radius: 999px;
  color: var(--accent);
  font-size: 14px;
  font-weight: 600;
}

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 18px;
  margin: 24px 0 48px;
}

.card {
  padding: 22px;
  background: var(--panel-strong);
  border: 1px solid var(--line);
  border-radius: 22px;
  box-shadow: var(--shadow);
}

.card h2,
.card h3,
.doc h2,
.doc h3 {
  margin-top: 0;
  color: var(--text);
}

.doc-wrap {
  padding-bottom: 56px;
}

.doc {
  padding: 32px;
  background: var(--panel-strong);
  border: 1px solid var(--line);
  border-radius: 24px;
  box-shadow: var(--shadow);
}

.doc h1 {
  margin-top: 0;
  font-size: clamp(28px, 4vw, 40px);
  letter-spacing: -0.02em;
}

.doc h2 {
  margin-top: 32px;
  font-size: 22px;
}

.doc h3 {
  margin-top: 24px;
  font-size: 18px;
}

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

.meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 14px 0 22px;
}

.meta span {
  padding: 8px 12px;
  border-radius: 999px;
  background: rgba(16, 19, 26, 0.05);
  color: var(--muted);
  font-size: 13px;
}

.notice {
  padding: 16px 18px;
  background: rgba(37, 99, 235, 0.06);
  border: 1px solid rgba(37, 99, 235, 0.12);
  border-radius: 18px;
  color: var(--muted);
}

.footer {
  padding: 8px 0 56px;
  font-size: 14px;
}

@media (max-width: 720px) {
  header.hero { padding-top: 28px; }
  .topbar { flex-direction: column; align-items: flex-start; }
  .hero-card, .doc { padding: 22px; }
  .nav { width: 100%; }
}